Yes the blind part and the fact there long(interruptive) is very bad, however if they fix those two things I don't have too much problems with it as whole.
Clash being situational and favoring the attacking player is kinda why I like it actually. Its not something you want to do when you are on the ropes all the time, like an X-factor or Ultras, or Combo breakers, those things are always good and have no real drawbacks(well ultras kinda do in super specific circumstances). In fact I wouldn't even call this a true blue comeback mechanic, its more like a way to potentially balance meter management out, like a meter deterrent, and at first I didn't like this, but that's because I was comparing it too much to MK9 breakers.
Right now the strategy of the clash mechanic doesn't come from actually using it, but from the threat of it, it forces both players to have to think very hard on how there going to spend there meter and if there going to even use the clash or not. It will be very good for mind games, specifically how you use it will vary greatly depending on the amount of health everyone has, the amount of meter, if you want to gain meter and save it to scare your opponent, or use the meter for straight damage, or save your meter to overpowered your opponents clash. The entire pace of the match will be dictated to how much meter everyone has.
This all however depends on how the other meter using abilities work, there needs to be a good push and pull balance between offensive and defensive uses. In MK9 the meter was heavily focused on the defensive aspect, the offensive options just were not good enough for most characters so you would always prioritize breakers, Injustice needs to find a good middle ground where ex attacks, roman cancels and super attacks are always a legitimate tactic and not a waste of meter.
As for the part about it favoring faster meter building characters, I think they need to balance the characters meter building power individually. They sorta dabbled in it with MK9, Quan Chi for some random reason built meter faster then every character. All specials in that game on whiff would build meter equally, 17 or 27 uses would build one bar of meter, depending on the attack, but Quan Chi had an attack that in 12 uses would give him meter. So simply put fast spamable fireballs would give less meter then a dragon punch and so on(should have done this with kabals gas blast and Nomad dash).
All that said though, I'm really only playing devils advocate, if they heavily change the system, or ditch it, I'm not going to lose sleep over it. But ya, with some minor tweaks it could be an interesting mechanic if pulled off right.
It was somewhat hard for me to articulate what I'm trying to say as I'm kinda busying working on something, so I may come back later and describe it a little better.
