I agree... Joey was totally right doing all those things, he was enjoying his time in London and, most importantly, he was happy.
Chandler was just being mean and it was pretty clear he wasn't happy. Plus, what did he want to do? Stay up in the room with Joey doing nothing all day? It's London, Baby! It's a whole new country, new things, new food, new-so-much-other-stuff, how can you NOT want to go out and walk around?