Given you never played PST before the EE came out, where do you get this stuff about 'crossing fingers' and comparisons of the versions from?
I've seen screenshots of the modded version at high resolution. The UI is not suitable at high res as it becomes tiny, much like the NWN UI does. There also is no mod that I'm aware of that adds TAB highlighting, a zoom function or a searchable journal, to name a few.
I've also modded plenty of other games with user mods and know how that goes. The mods for older games are generally older mods that are no longer supported, and many times you do have to cross your fingers and hope your game doesn't crash or introduce some new compatability issue. It's called Modding Hell for a reason. I should know, I've been there. Several times. I am a Planeswalker.
But beyond that, unless you are suggesting that using a variety of user mods cobbled together on your own is more stable than a professional retooling, packaging and supporting of the game like what Beamdog does, I'm going to just have to disagree based on personal experience. And I don't think you would suggest using old user mods would be more future-proofed for future operating systems updates as well, either, right? The whole customer support thing helps, too, so while Beamdog does use mods in their build (yes, I am aware they used that fellow's mod package in the EE) they also actively support them, so if you have an issue they will answer you and help you. They will also patch the game as well. Seems like a very good deal to me.
And if you still think all of that isn't worth an extra $10, then I again point you to the fact that we are discussing PS:T in 2017, and many people on Steam are doing the same. That alone is a great thing for CRPG culture. More of these EEs generates more discussion about the classics + generates public awareness of CRPGs = more CRPGs for us in the future. It's a pretty simple concept.