It sounds too good to be true, I don't think the Developers want us to progress that fast and hit the end of the tunnel so soon though... Luck plays a huge factor in determining our progress, if you take away all the bad luck, all the good stuff will leave the game unbalanced and we will get bored of the game very fast.
The initial idea was just to sieve out heroes and monsters that is capped at 3 stars.
The dev can choose to put in more 3 stars heroes whose max potential can be either 4 or 5 stars, where 4 stars max potential will have a higher acquisition chance. It doesn't necessarily have to be 5 stars to appear in the 400 gems pull.
The outcome of sieving out of cap 3 stars heroes would be the provision of limit breaking 4 stars hero to be at least usable in legendary modes and stand on par with 5 stars potential heroes.
The focus on 4 stars heroes have been decreasing as of late and I think it is quite important to place focus on linear character progression and development since the game is less than a month old.
In the end, I believe the developers want us to try all their heroes and through this, maybe the 4 stars heroes could play a larger role in VF compare to now.
That is still taking away all the bad pulls don't you think? Heroes/Monsters capped at 3* appears in majority of every x10 pull. Take that all away and you'll get increased chances of getting 5* potential heroes which will speed up our growth substantially that the game content cannot keep up. Then the job keys would be the only wall standing between us and the end of the road.
Aside from Job Keys, there are also several other factors that prevent us from hitting the curb:
1. Runes
2. Equipment
3. Faith
4. Gold
5. Fodders
6. Aura's positioning
7. Luck
Hitting end game content isn't as easy as obtaining just the correct characters to keep up with the content. A very good character at the end of the road, can only be that strong after limit breaking +10. Only through enhancements, rune upgrades and setting up of aura positioning will allow you a smooth sailing journey.
Regarding the removal of bad pulls, is not 100% correct. Why do I say so?
On the surface, many people will think the same way as you do because removing "bad pull" = "higher chance of getting good pull", this thought process itself is correct but not 100% because you're only looking one step ahead and not any further.
Within this "higher chance of getting good pull" you need to consider the few curbs that I've factored above.
What is consider a good pull? An Athena Vincent or an Ares Vincent? What are the chances to obtain that ideal faith? What are the chances of pulling a 5 star potential in the first place? What are the chances to get the specific job that you want for a class? What are the chances of getting the squad you want for your arena or event dungeons or pve content?
Bear in mind that during events, Event heroes have increased acquisition chance and that itself is in a way, similar to removing bad pulls but also obstructing your chance of getting a legit good pull. The developers can also use this chance to juggle the factors of getting that ideal character as well.