The problem is Goram and Sylphi are only available from CS.
I agree that Lilith should rework the older heroes, especially the ones that are farmable from Heroic Campaign, and slow down the release of new heroes, like one each month, not 3 new ones (log-in, CS, event) every month. There are so many heroes in each shop that makes it hard to focus on a few.

You maybe right. But I also complain about Taurus, while I have him in good shape.
Sylphi is worse. She is not available to everyone (I personally spend quite a number trying to get her with no result. But not so much to get her by ss), but gives ridiculous advantage.
At level 87 it was not problem yet, now at 88-89 she already can wipe out most of team alone if starts her ults one by one.

Why people do not experiment with other heroes? Simple: I have Alana 65. I was trying to make her useful (end could even increase dmg output on some raid bosses). Bam, now know she was waste of resources I could use for something more useful.
I have orange chrona... cannot put on any team (paid hero!). I have better invested this in Tashi.
And quite few others like that.
So these experiments may give slight advantage somewhere in the road to lvl100, but chance of loosing competitiveness is much higher.
And loosing competitiveness in most cases means less ss, gold, diamonds, upgrade dust, etc. So you are falling behind even more.

So that's only right tactics: invest in proved heroes and if have leftovers: in new heroes, hoping they will be op.

Have not seem miracle yet, like person with amber found right unconventional team and became top

Three new heroes in eight days is a bit overkill... I was only able to get them to P4 in their 90' and one is still severely lacking in skill points...