The main reason why this complete 15 trial thing is inherently bad for the game is due to the fact that VF is at its core, a gacha game.
On top of being a gacha game, its a gacha game where the heroes you get heavily skew how far you can progress in the game.
Due to the fact that VF's game design is fundamentally flawed from the start, having the 100% hero reward placed behind a gear-check wall isn't helping. Why do i say that the game design is flawed, let me explain:
Not saying a gacha type of game can't succeed but the fact that the heroes you get are all very different with lots of strengths and weaknesses makes lots of heroes strong and at the same time others extremely weak.
There are other gacha games where there are wide selection of collectibles but that's basically it, they are all collectibles, not must haves. Sure metas will develop and some will become core units and what not but it't not like VF where not having the meta units will hamper your progress significantly.
For example:
Trigger archers, cybella, kane
Summoners, sven, tali, sora, matilda
faye, lucille, units for sdd setups etc
If you don't have any of the above don't even bother about raid. Legendary and above difficulty also use a lot of those units as core setups. Everything in the game is now balanced with these units in mind. Imagine if you didn't have any of these units, you would scream out that content is too bloody hard. Now why is it so hard you might ask, precisely because of the above units and the trigger system in place.
Arguments against these would be ability to use ally units, valianites for exchange of both summoner and regular units as well as pixies. Yes sure you have all these to ease the content for you. But you can only have 1 ally, you still need the other 4 units.
Exchanging for a unit+ pixie costs an exorbitant amount of gems, even more so for a summoner. you might take 2 months or more to save up 30 val if you are purely F2P.
So what, everyone can still get the units they want at some point in time. This is the crux of the issue. How many months can it take for you to properly form your SDD team? How much to invest to make 1 trigger archer max crit? having 10k+ damage on your svens? 20k hp on Faye? All of this takes time to build up and maybe after 3 or 4 months you got a super good SDD/ trigger team or something. By then maybe the meta has shifted due to new units/gear being introduced. So maybe 1 or 2 of your units are rendered obsolete. Then your hard earned val you used to exchange for the units goes down the toilet. Hardcore players / p2p players don't feel as much pain for the transition but the casuals / f2p suffer the most.
Now back to the 100% reward, for those newer / undergeared players, completing 100% is a long shot whereas more seasoned players can just breeze through the content cause they have the meta units already. So now the stronger players have this free hero basically granting them a further 15/20 val lead over those who couldn't get it. I don't expect someone who is new to complete 100%, but someone who is 2months+ into the game can hardly be considered a new player.
You imagine yourself as this newer player, you can do all the quests except 1 so you can't get the 100%, what do you get in the end. Basically close to nothing if unlucky. Lots of equipment/hero tickets are given but its no guarantee of 5*, not to mention completing the set. (Excluding drops from the events itself) Sure you can exchange for bazaar items but so can the stronger player (at a faster rate even) but bazaar items still include rune tickets, hierlooms so progress can still be made from there. But its painfully slow. Hierlooms take an exorbitant amount of gold and time to up 1 set to 4/5/6*, runes are also heavily RNG based and majority of runes you get might be useless and simply fodder material.
Ask yourselves this. What do you play the event for. Honestly.
100% chest + legendary drops and bazaar items obviously. So you take away the 100% chest and legendary drops will you even still play the events. For the new and upcoming player, they may go through event after event with little to no progress because they cannot do legendary. It may take months before a player can have a good team to consistently clear legendary content comfortably. What will happen before then, they quit the game obviously. At least with the 100% hero there is a sense of progression. Honestly is giving them the hero spoon feeding them? you still need to work for your gear, runes, MLB and faith. On top of making a proper team.
RNG isn't the problem, you look at Diablo 3 now. RNG all over the place yet you can still play and be happy with the game, not feel salt at every turn. If you play the game and spend the time but gain little to no progress, it isn't player friendly at all, even more so for a mobile game where players may have the majority of people may be casual players.
*Saves gems for 1 month. Spends 3k gems on new event to pull new hero. Gets almost no 5* potential and no event hero.*
How will you feel. bloody salted i bet.
*Struggles with raid since the start. Finally have enough for full set. Exchanges for champion set. Wiz / Def / Wiz / Zodiac. Spends 30+ val to reroll everything to trinity"
How will you feel. bloody salted i bet.
*Spends months waiting for valiant tickets from both login and arena. What do you get. Kiera Kiera Kiera, oh kane! hercules faith. Faints oh a darrion! hera. Freya! Athena*
How will you feel. bloody salted i bet.
Why do you think the player population has plummeted so badly? The nature of the game requires you to invest lots of time so that over the long run the RNG evens out. Casuals can't have that.
I don't need the game to be easy mode, i play this game a lot and can afford the salt, i come from games even saltier than VF. But if the game cannot at least cater to newer players / casuals it will just die.
When i mean cater i don't mean spoon-feed them, but provide them an appropriate path of progression.
You tell people to git gud, but do they have a way to do that consistently? Depends on luck most of the time.
Lucky = get the hero/gear you need. unlucky = wait to exchange using valianite
Its no easy job to balance for casuals / hardcore / f2p / p2p players but the devs have pigeonholed themselves into a corner with the trigger system. No trigger = no DPS / Trigger = absurd DPS. How do you even balance this. Obviously not by releasing hard to get heroes with trigger abilities.
Just my wall of text rant about the current state of the game. you may not agree with me, but frankly its my opinion and you don't have to share the same one. Everyone has different views and so be it, i just hope VF survives.