Not sure how this relates to stickers and decals, but I'll bite; however I'm making an assumption that "grass music" is a reference to bluegrass music. If not, disregard everything I'm going to say here...
Having lived as a young and enthusiastic person through the "1970 and on" half of the big bluegrass period, I'd observe that that popularity period was a function of more than just music, just as, for example, the popularity of MASH and All In The Family was more than just a function of TV programming. Bluegrass "1970 and on" was culturally at the right place at the right time to become what it was, just like disco and a number of other genre that had much shorter-lived popularity were. I don't expect that combination of right-place-right-time conditions to happen for bluegrass again within my lifetime...
While I expect bluegrass to live on, it's going to have to mutate in order to fill a need for the young folks who are going to take it over. In this current period, that transition is still very active and there are both subtle and not-so-subtle conflicts happening between the old guard and the the younger generation. I expect these conflicts will continue until most of the old guard pure-bluegrass folks are out of the music scene...
Until then, any top-level performers are gambling with pure bluegrass. Their possibility of success is much more likely if they spread their talents between bluegrass and other country or roots related genre. This of course does not endear these performers to the pure-bluegrass crowd, but it keeps food on the table and gas in the tank.
There are some top-level pure-bluegrass performers out there, but since at least the early '90s, money for top-level performers in bluegrass has been a drop in the bucket compared to more popular genre, so those performers have to live very carefully to survive. That is not much encouragement for any band to make a full-time commitment.
All that said, I don't see a huge amount of sticker or decal use on bluegrass double basses, just like I don't see them a lot on guitars, banjos, mandolins or Dobros. That probably comes from a general respect for old wood and old instruments. But there's no rule or anything like that for double basses that I've ever heard about.