HTML in the middle of PHP code is icky, and should be avoided as far as possible. It's not that critical in rarely used areas or system-provided messages, but should really be outed to templating wherever reused HTML structures and dynamic data containers are involved.

Wherever I may have HTML in whatever I code, it's because a certain area was rushed through and I haven't yet gotten around to switching it to use templating. This is usually what you see in draft production when you are ironing see more out the basic workings of your code.