Regarding the new heroes they also end up being released in the game shops, something that many games don't do. If you don't want to wait for the hero to be released you can buy it, if you don't want to buy please have some patience.
1. Some heroes supposedly will never be released - like Ezio and PoP.
2. "you can buy it" is a very unfortunate choice of words when we DO NOT KNOW the price, feels more like helping a nigerian prince than buying something. That's why everyone is up in arms about CS drop rates and not so much about upfront priced events like souls bonus purchases. Sure, they make fun of cosmetic skins "valued at 30$" when they were never sold at that price but no one grabs a pitchfork over it.
3. When there are quite a few really good or even "must have" heroes released at the same time (Ezio, PoP, Ling Ling, Silphy, Goram, Desmond, Orkon, etc) and not available in game shops kills the competitive aspect of the game. The problem is not that they are released ahead of time for a high price but that there are so many and so powerful compared to farmable heroes released at once that the power creep becomes insane.
4. I'd play pokemon if I would want to wait and "collect them all". But wait, unlike pokemon, I need arena currency, epic arena currency and HoL currency to collect them.
PS. Welcome back, we missed you.