I wouldn't say it's rotten to the core, and there has been a lot of technology over the years to make it better (and you can get pretty close with high end solutions). And I boiled it down to its simplest, but you get the point.
And remember, MIDI isn't just there to play piano. It's designed to provide a reasonable representation of any instrument out there; however, it pretty much uses the same rubric for all of them, when in fact every instrument is different.
Interestingly, from the listener point of view, the most vocal critics seem to be from folks who criticize the sounds of their own instruments.
But if you are looking to get a good performance from notation, then unless you are using a MIDI rendering engine that provides humanization capability (and that may not be the way "you would have done it"), you are going to get every note on the exact division you wrote it.
Here's a good test. Play a song on the piano (even using a metronome to keep yourself in time), and then look at the result. You will find very few of your notes land on the beat divisions. They might be off by 1/64th, 1/32nd, maybe even 1/16th. If you look at the result in notation view, it looks like someone just splattered black paint dots across the page.
I don't know if there is a free trial version (you should check), but you might want to try Native Instrument's Kontakt Instrument called Alicia's Keys. It's $99 to buy and works with the free Kontakt player, but you don't get all the bells and whistles then like you do with the full Kontakt player.
You might also want to take a look at True Pianos.
But again, the "performance" of the MIDI has to be right for it to sound right and that's the hard work part of it. No short cuts.
It's not the sounds of the VSTs and such I'm criticizing, as mentioned, demos sound fantastic. My issue is I can't get that from a notation export, and nobody, but nobody, has been able to tell me all this time that isn't going to happen, rather "buy Miroslav" and the like, and you'll get a realistic performance. It's not going to happen from notation, I now realize.
For my purposes, I disable humanizing aspects when doing notation, seldom actually copy anything into a score played. I made a mistake doing this sometime ago, in fact, the playback sounded correct, the notation WRONG! I was aghast I had to redo a couple passages, because the humanizing stuff my lazy rear had pasted from this new software, for instance, gave a note 1.69 duration on playback, only, and I'd never tried the unmolested playback. I had no idea this was happening. Interesting the program, bottom line, "knew" what I played, but did not notate it right, and there are no 1.69 longer notes coming from my fingers, which the software actually notated with an entirely wrong beat I never once played. Again, the program "heard" what I hear, and, also, I do play evenly such as the work I was working on at that time. I manually notated the passage correctly, to sound as it did humanized, which the application botched the notation of. At that time I also had a latency bugaboo to deal with, had to slow things down too much, didn't even find the live input worth it, for having to manually clean it up, haven't needed the humanzing stuff before, anyway. I have never since allowed such played notes to "touch" a score, that they don't play as intended, humanized off. Tell you what, it's major medical, when a passage is botched in the middle, if you don't luck into an acceptable new boundary with the concatenated measure, or bar, that picks up again, where the editing stopped. You could jeopardize days of work. I do, more than anything, agree that proper notation is what I actually play, would not compose at all, if on paper was not exactly what was conceived, with rare exceptions, a little thing or two that gets compromised, cop to a fermata or something. And what I manually put on paper is what I play, if it's a work I play, only plays back like a computer plays pianos, not a real piano, but it's not as if the notation and playing don't match in all aspects of the primal beat, notes durations.
In terms of shortcuts, I came to the same conclusion, even found this company on the web today that makes a midi a performance, for a handy fee. I wouldn't sacrifice time composing to do this, unless I had nothing else to do. As you indicate, that would be like a second job, when the composing is all-consuming.
Thank you for the tips on the two products, though. I'll look into that, am not going to just give up.