was COHO store mechanic good?
Depends on your perspective. If you were a casual player it was great, you could get everything for free eventually. If you were a competitive player it was shit, you couldn't use the best stuff every game unless you paid money for supply because you didn't get enough free supply to be able to constantly repair the good stuff.
It was like, you'd get 2000 free supply on average after every game. That was enough to ensure you could use, say, common and uncommon items every game (in CoHO those were things like intel bulletins and hero units, in CoH2 it'll likely be bulletins and commander abilities, though we don't know yet). However, the most effective items were rare and extremely rare, and they cost more to repair. Therefore, if you wanted to consistently use those rarer, better items, you had to purchase supply from the store. If you didn't purchase supply, you would have to cycle out rare items with less rare ones some games until you saved up enough supply to repair the better items.
This was a big problem in tournaments, because you were obviously playing a lot of games in quick succession and wanted to be able to use the best stuff every game, which was difficult without paying because items would last around 5 games before they broke and couldn't be used until they got repaired.
Ultimately, it was great for your average player because everything was available for a price (there might have been drop-only items, I can't remember) and you had something to constantly work toward, but it was pretty awful for anyone trying to compete because if you didn't pay money and your opponent did you would often be at an item disadvantage.