I know that they're not going to kneejerk shut my account just because I received a bank transfer from a cryptocurrency exchange. I trust them more than I trust the regular high street banks to not try to screw me with hidden or unfair fees. If anything ever happens to me, I feel like they'll be helpful to my wife and family, whereas a regular bank would just shrug and say "Sorry, can't help!"
By the way regarding the "extra fees", the standard account fee (£60 per month) is waived if you keep at least £25,000 in your account, and normal day-to-day online personal banking transactions are free so I don't actually pay any more fees than I would with a normal bank.
