Many people preferred FT to PS (I know I did) and still would if they had the choice. Having PS behind the company now, with their stellar support and obviously better business practices, it's a huge business win for PS to maintain FT's brand and market it as its own site. When US regulation happens and assuming they're allowed back in, which it seems is possible now, there could be a large marketshare that preferred FT before BF that will return. On top of that, PS now comes off as the hero of online poker not only because they paid out their own US players very quickly, but went above and beyond to step in and bail out FT's players as well. That's a huge win PR-wise.
Many companies buy up their competitors and maintain their branding, in fact I would argue that most successful companies would jump at the chance to acquire their biggest competitor if the terms were favorable. There's a lot about marketing that involves brand loyalty -- by acquiring popular brands you keep those loyal customers who might otherwise bail on you, or in this case might not return to poker at all. So this isn't at all unusual, at least not here in the US. Maybe it's a difference in the Euro business mindset but I don't see what the surprise is about? Makes perfect sense to me!