The cruise market at CWL has long fascinated me. For an airport that serves a relatively challenged economic core catchment they seemingly outperform when it comes to cruises. With BRS's catchment containing a high number of fairly well-off, older, often retired people (one of the reasons Barbara Cassani said that Go went to BRS), it might be thought that they were the ideal cruise passenger, although I believe that in recent years cruising has become much more popular with all age groups. It's not something that has ever attracted me.
Part of the answer might lie in operational capability with, until the advent of the lighter former First Choice B 767s, now disposed of (fewer seats than TOM's own aircraft), BRS would have struggled to fly non-stop to the Caribbean.
Now the 787s are available the operational question might not be now as focused as it once was, but the cruise market seems established at CWL so perhaps TUI believes there is no reason to change things.
It would be interesting to know how many people from the West Country and wider South West use the CWL cruise flights.