You even said it yourself, you're making an exaggerated point.
Quite true, not to mention that when people complain about the options that have been "removed" from Skyrim, they always seem to forget ones that were added or returned from previous games. Things like smithing, the echanting skill, romance, the ability to participate in the economies of communities, things like that. Now, maybe you don't necessarily feel that these things make up for what has been removed, maybe you don't even care about them of them, but regardless, when you want to argue about "simplifying" the series, completely disregarding the things that have been added and only acknowledging what has beem removed doesn't really help to make an objective discussion.
Another thing that people often fail to consider in this sort of discussion is that no developer, Bethesda or otherwise, can ever hope to include every option or feature someone could possibly want to see in the game. Developers have limited amounts of resources available to them, and with these finite resources, they need to believe what they believe will be the most successful game possible. For this, they need to have priorties, they can't just add everything they think of that might be a good idea, they need to consider whether the payoff of adding it will really be worth the effort, or indeed whether it fits the game they're making at all. And sometimes, they need to drop some features they'd like to add so they can have enough time and money to work on things hat will ultimately have a more important impact on the game. It may be rather extreme to say that mysticism was pointless, but I'd certainly say its impact on the game was smaller than the other skills that have been confirmed to make the cut, seeing as the spells that were previously from mysticism made their way into other schools. After all, the magic skill we get to replace mysticism (I'm thinking of it in those terms anyway seeing as it's the only magic skill in Skyrim that wasn't in Oblivion.) is enchanting, and what that does isn't something you could easily justify putting under a different skill. While options are generally desirable in RPGs, there's no way a computer RPG can ever truly offer total freedom, and having too many options can actually be detrimental as the more options there are, the harder it is to ensure that each one has the proper concequences, and an RPG isn't supposed to just have options, it's also usually expected that the options will have a noticable impact on the game. Another vital part to ensureing that your options matter is choosing the ones that will make the most difference in the end, so sometimes you still have to be willing to sacrifice some features you want to do for ones that you'd consider more important.
Now make no mistake, I'm not saying I'm happy with every single decision Bethesda has made with Skyrim, but then again, I could find things to complain about in every game I've played before if I wanted to, I'm sure, the Elder Scrolls or otherwise. I'm just saying that sometimes, it helps to think about the possible reasons for the choices made by the developers before criticizing them, and that sometimes what initially looks like a detrimental move can actually have benefits, though you may not see them initially. Perhaps after thinking of these things, you might be happier with those things you initially complained about, or at least may find them more understandable. And if you still don't like the choices, then you can complain all you like, at least then, your complaints seem more objective if you don't ignore factors that are contrary to the point you're trying to make.