Just hit the upgrade button and move on with your life, I did and made it through all 3 heroes to max without having to gem.
You want... you want... people in he!! want ice water too.
Pretty sure the developers wouldn't really have much of a say in the matter, you are better off asking the accounting and finance department and whoever approves any major changes to the game (possibly the board/shareholders especially if it it something that affects their revenue stream).
I'm not going to waste my time reading all the posts in this thread because this has been requested/discussed to death since 2014.
Here is an "official" response from Supercell's Anoushka:
https://forum.supercell.com/showthre...=1#post3415784
Note that was in Dec 2014. If Supercell wanted upgrading heroes to be available in war and/or if it was easy to implement, don't you think they would have done it by now? Please stop asking.
You won't get a response from a developer.
This dead horse is getting tired... The answer is gems.
if only they would introduce cosmetics for heroes they can relax a bit on the $ problems. probably would make heroes available for wars.