For the first highlighted piece of text, it may not be that simple. As we both know some set-ups are more beneficial for the person pressuring you (Good example being kenshi throwing out an Ex SC near the corner from a solid range. It will beat most characters' armor, it will hit most jumps, it will beat your normals, and it will check you up if you block. Obviously, Ex SC has a high success rate in this case). Apply a similar to thinking to potential set ups things like interactables could create, fighting games are not that linear to the point where you can say "oh just pressure him if he's near an interactable" because it is never that simple. The fact that the interactable forces you to alter your decision making process creates another variable that again is unnecessary.
Character variations are constant once selected. Once you pick it, you are locked in for the remainder of the match and have options to that characters new moveset. If i pick stage y do and get p1 side do i always have that interactable that is available stage y? It may be closer to p2. It's like picking kenshi and expecting to have access to a scorpion spear, it makes no sense. It's not equal, and you do not know how it will play out.
We don't even have stage rules for the game, if we pick stages we are definitely going to create skewed match ups, and if we let it random are you really content on leaving it up to the game to determine how hard/easy it is going to be to win a match based on the stage when you just paid a couple hundred to fly out and play in an event? Idk about you but i'd rather leave it up to individual skill. We saw it in Injustice and MK9, interactables do cause imabalances this isn't even a debate tbh, NRS themselves nerfed stages because of the opportunities it created for certain characters over others.