Hmmmm, I hate the entire stinking corrupt system.
I don't know how they get away with tacking on seemingly unsanctioned methods to extract more cash from you. "Oh you've done a SAC? That's a 10% loading, thanks". "Oh, you had fish fingers for tea last Thursday? That'll be another 5% please". "Insert some other random excuse for theft here...." etc etc. I say unsanctioned, because as you say, not all insurers hit you with the same bullsh*t loadings. There's just no consistency to any of it. Ambulance chasers, bodyshops, autoglas, main dealer franchises, the government.....they've all got their fingers in the insurance pie. The government don't care because they're getting their IPT regardless, and the insurance ombudsman/governing body are about as proactive and fast moving as a glacier....and I'm sure there's some of the pie left for them, too....... but what can you do?
Move elsewhere, that's what you do! They rely on people blindly renewing, but don't give them the satisfaction.
I would say bonus protection is worth it, but legal fees? Hmmmm, not sure on that one. As above, they're all in bed with each other. We all know claims go 50/50 these days, regardless of fault. So just get the minimum cover you feel comfortable with.