Hum... I'm not sure I follow. I mean the cross-up would still be ambiguous regardless. If you had to hold the direction of where the attacker is, you would still get hit by ambiguous cross-ups due to the nature of the 2d square hurtboxes. If the attacker is directly on top of you, how do you know which direction he is attacking from? Unless you mean they should make it so you just have to hold forward or back and it would always block both sides... That would indeed make cross-ups work more like MK (and completely ruin SF in the process lol)... But I still don't get your point.
Sorry, it was a really terrible explanation. Rather than trying to work out what "back/away" is based on the position of the attacker and the defender, base it on what direction the attacker is currently facing. Example:
Player 1 is on the left side of the screen and facing right.
Player 2 is on the right side of the screen and facing left.
All the while player 1 is attacking player 2, player 2 needs to hold "right" to block (this works as back to block) and vice-versa.
Now, player 1 does a jump-in attack and tries to land the hit on the other side of player 2. All throughout this attack, player 1 is facing and moving to the right even when he passes over the middle of player 2, hence player 2 still blocks by holding "right". Once player 1 actually lands, player 1 will change facing to face towards player 2 (now left) and player 2 will need to hold left to block subsequent attacks.
Basically, a back-to-block system that removes cross-ups and most unblockable setups (being hit on both sides at once) as you always know which direction you should block. Injustice removed a lot of unblockable setups (such as projectile on one side and normal attack on the other) by block being determined based on the direction of the attacker. Expanding it to the facing of the attacker would remove the remainder of them with the exception of the odd auto-tracking move.
Ambiguous cross-ups are not an "unfortunate side-effect" it's just different mechanics that you don't really like because you're used to being able to block everything by holding down a button. You're talking like cross-ups are the most horrible thing that plagues fighting games and that Capcom should get rid of them completely in all of their games...
Please don't tell me what I'm used to - I can handle block button and back to block games just fine. In addition, you still need to pick the right height level with the block button so it's not just block everything by holding down a button (again, I hate the unreactable stuff and the sheer amount of setups that turn blocking from a skill to a guess are what put me off playing the game).
Ambiguous cross-ups and unblockables have become part of the SF play-style but that doesn't mean it needs to carry over to all other fighting games. In addition, if a game implements a back-to-block system it does not need to automatically inherit the side-effects (intentional or otherwise) of that system. Very few fighting games innovate with their blocking/guard mechanics and it generally comes down to "back-to-block 100% SF style" or "overly simplistic block-button". Injustice mixed up the B2B formula more than most people realised.
Also as much as I'm not a fan of Marvel this was pretty random and unrelated to anything...
Capcom ain't perfect
Also, I still say that if a game uses a block button that becomes active immediately and has zero recovery when released and doesn't add any other blocking mechanics to the game, then the block button becomes completely redundant as there's no reason why you won't hold block when stationary. At that point, you may as well remove the button completely and implement neutral guard as functionally there is no difference (when you're neutral, you're always blocking).
