Though. One thing regarding Street Fighter x Tekken is that it was based on Street Fighter IV and targeted to that crowd, and as can also be seen by SFV; the community is more around tournaments, competition and balance. So anything that throws that balance out of the window is received with backlash.
Injustice 2 comes from not only a sucessful first entry, but also from a sucessful mobile game that had consumables all over it.
It also comes from a developer that for years found success in catering local and random fun matches, while adding chess, puzzle, cart racing modes to their fighting games. Even optional adventure modes. To even completely unbalanced games like Armageddon and sillyness in Test your Luck modes in recent MK games that throw random variants to matches.
So, even if it works the same as the gems in SFxT, the community of Injustice could be more receptive to it. I for example, had fun with the gems in SFxT and continue to play it on Vita. And impressions online about this seems many are excited at the prospect of customizing Batman and beat their friends with him.
As always, only time will tell. If things don't go well, is not the first time the developer changes mechanics and reboots a franchise.