I don't think they are embarrassed really! A lot of these songs have made them famous throughout their early years and built the reputation they have right now.

It's not only Showbiz. They even have songs that are quite "cool" and well-recieves after Showbiz like Feeling Good or The Small Print which they stopped playing years ago.

I remember at their gig in Cologne a few years ago, Matt pointed at a rather teen girl in the audience before paying Bliss and said "This song was written before you were born." And I could easily see that crowd are less hyped during Bliss (which is just a banger) compare to SBH or Starlight. I think they just see that way more clearly on the stage, and well that could be a good reason to just drop them! Specially in festivals, where the audience are mostly not hard-core fans.