For two examples:
I've actually been pretty pleased with Lightroom/Photoshop as SaaS because these apps still often have new innovations that actually make my life easier as a hobbyist photographer. Thus I don't mind paying per month because I'd probably already be upgrading to the new version every year anyway and this is just spreading a similar cost out over time.
OTOH, Office's switch to SaaS is what finally pushed me over the edge to using free ("as in beer") alternatives... they can keep rejiggering the UI this way and that way but I can't imagine what they would add to Word or Excel that would make them seriously more useful to me, it was never a must-upgrade for me (YMMV if you work in an enterprise office setting or whatever) and thus the SaaS move is not good for my usage.
Compared with Office 365, you don't get the free 1TB of cloud storage, the 50GB mailbox, the full online versions of Office, the ability to stream Office programs without installing them (so you can use them on, say, a cybercafe PC), the add-ons and extensions, the cross-platform tablet and smartphone apps, the free upgrade to the next version of Office, and so on.
Office 365 is a huge ecosystem play, whereas OO/LO have no ecosystems.
Otherwise, UI changes are annoying, but the basic Office UI hasn't really changed since 2007. It changes less often than, say, Gmail.
Isn't this one of the big reasons for the rise of SaaS apps, though? Developers, unlike musicians, have found a way to combat piracy in a way that both consumers seem to prefer (lower upfront costs and usage based pricing) and developers benefit from (more revenue over time in exchange for delivering real value).
Besides, being forced to provide 3 months of free usage without any say in the matter is hardly defensible due to piracy. It's even less defensible when the party enforcing the free usage is the party that stands to benefit most from it.