Tara never got any stick (we all know she wasn't one for the timber) for falling for Willow, or maybe thats it.
Maybe the 'hate' for Satsu stems from the fact that she is the non-buffy part of a big change that most people don't like.
I (as has been stated by many others already) do enjoy Satsu, she's an interesting character... and brings a good mix to the fold. However, I would like to see a more main Scoobies centered arc. I want to see some (non sexy) B/W/X and possibly Gman action. I don't think that's too much to ask.
Also-Tara did get a lot of flak when she was first introduced. Now, of course she's one of the most beloved characters in the verse, but that was not always the case.