You can test aspects of 1.1 by yourself or in friendlies. You have no idea how it will effect the game unless you analyze and play every possible matchup.
Banning MK means you're not really testing anything. You're just needing to learn a larger variety of matchups, and learn material already present in the game.
In fact, banning MK is actually less work than this is. It doesn't require any testing by yourself, as the results are fairly obvious. You won't be fighting Mk anymore.
Not having the game is really altering your sense of reality. If you've actually played 1.1, changes are so far and few between, one only needs to slightly alter matchup analysis once people note the most obvious changes, that can be seen by anyone actually playing. One can easily "analyze every possible matchup* just by noting these changes and having light discussion.
Throw setups last for a lesser percent. Most combos still work, and may or may not last the full %. A *few new setups are made, which are slightly better versions of setups already known, because of the extra hitstun. Even though these throws lasting to a lower % still take into fact that the reward is still similar, because they can kill earlier.
Banning MK means you have to do a thorough analysis of new tournament trends, and closely look at matchup analysis on many characters who now have a much higher chance to play each other without resorting to MK in a set. It will require much work as a united community to gather this data and observe the changes in the metagame. You need to learn LESS matchups with MK gone, because there's one less character.
Results are not fairly obvious. Was there an overlooked counter among the high tiers with MK banned? Which characters are able to flourish or stagnate? How can previous MK mains cope with this new situation, resorting to focusing on their secondaries? There are many sources of information to keep track of.
It is still possible to do much of the above with 1.1, but I was only talking about just testing 1.1 compared to testing an MK ban. You don't just make MK be banned without having the necessary precautions and looking for specific sets of data over time.