Sorry but I have to agree with
@Purple Orange.
Whilst the HSTs are iconic and their legacy will continue for years to come, the seats were worse than the 800s I feel, they were noisy and the tables were at a ridiculously low level (I'm just shy of 6' 4" and my thighs barely fitted in the gap between the seat and the table). I actually thoroughly enjoy the acceleration of an 800, especially on electric, and when travelling from Temple Meads to Cardiff I will even get XC up to Parkway and get an 800 across to Cardiff as opposed to a 166 or a HST.
People don't like change basically, and people cannot adapt to new things. It'll be the same in 30/40 years time when the 800s are retiring and even newer trains will be introduced. 'Ooh but these new trains are awful and plastic-y compared to the 800s'.