The Stronglight I use (JP400) seem fine, when I can find them in the sizes I need, I don't think they've ever covered the range Shimano have. I also pay less for them than UN55's.
So the question; have Shimano stopped selling UN55 bbs and is this all part of a move to make us convert to external bearings and fugly modern chainsets?
It's been a long time since anything other than Shimano's budget chainsets used ST, it was inevitable that the BB's would drop to the same quality. I doubt they feel any obligation to support discontinued components. Production stopped years ago, it's an indication of the scale of the business that some are still available.