It's actually quite simple. I see no need for hunting down a boxed copy.
Me neither, when it's so easy to work around the "house rule". Could also be a higher chance of a boxed copy not working properly on whatever machine you have. That's one of the big upsides to buying games on GOG.
Not a fan of ToB either. Fine to complete it once or twice just for the experience of it, but the base game is much better, and much less linear. I did love the Watcher's Keep though, so that is well worth playing at some point.
If you go for the boxed copy, best of luck to you and I hope everything works perfectly :) Just stay clear or the "error-loaded edition" and you should be fine ;)