Emotional reactions to theories - other than perhaps perplexity or wonder - continue to amuse me. Why would we desire to supplant a theory that holds so much promise despite it's absence in experimental science?

I guess beauty is indeed in the eye of the beholder. Granted, to visually behold more than 3 dimensions + time is a challenge with our eyes and senses limited in the 3D + time world. However with some well used and readily understood mathematics (for those who care to wander that path) we can in a fashion extend our senses and draw 2D models (or build 3D models) of the higher dimensions. These models appear visually complex and unreachable from our braneworld - but the math behind them is not.

Now, the development of new math to further extend the string theories can be left to the likes of Witten, and I think that this is what he refers to when lamenting complexity.

Besides 50 years is not that long. 2400 years or so ago Democritus postulated the atom. Aristotle and others rejected it and it took another 2000 years for Dalton to pick it up and try again - this time with the advantage of accurate quantitative measurements when combining chemicals (Lavoisier). It then took another 50 years for the theory to be generally accepted. I'd say we are comfortably ahead of schedule if we are to accept Witten's 50 year wait plus the 90 years since the first postulation of string theory. Interestingly string theory also, like Democritus' atoms, underwent a falling out of favour and revival.

GUT - may be observable from proton decay. The now repaired in 2006 Super-K III may find it.

Supersymmetry - observations possible with current technology in 5-10 years. This may also yield clues to the nature of multidimensional space.