I think everyone likes Bass. I just think that everyone sees him as a player who has some value that's fairly replaceable.
He's an undersized PF who can't play the 5 spot.
He can hit the jumper well for a big, but so can Sullinger.
He can finish well on the break, but so can Wilcox.
And with Green potentially playing more 4 as the season goes on, we could cover the 4 spot in his absence, not even taking into account that a trade involving Bass would likely involve bringing in another big like Gortat.
So yes, I think he's very good at what he does. However, I think he's replaceable, and that's why people are more likely to use his name in trade talks. Also, his salary helps, as a combination our young players doesn't add up to enough to bring back much salary.