That's an excellent point and it's indeed something that happens quite often. In our 4e games this was always a discussion-starter: "Hmm, so our Ranger is already out of surges again. Shall we continue, nonetheless? How's everyone else doing? Alright, since everybody else is still fine, take good care of our Ranger and make sure to keep him out of trouble. On we go!" This is why sources of healing that don't require the expenditure of healing surges are so important and desirable. It's something all of the players were looking out for. The most common source were Leader Dailies, but there are a few others, as well.
It also reminds me of the 'Healing Standard' our party managed to get hold of in our first adventure. We quickly decided it was the "MIP" of our group: it saved our a**** in countless encounters that might otherwise have resulted in TPKs. In case you don't recall what I'm referring to:
Yeah, I gave BSoH to the first party that I ran 4e for in 2008. It was a great way to kind of smooth out some of the "the fighter is down to 2 surges again, and we're still 15 miles from home..." But you're right, the players just had to learn to either NOT let that happen, OR change up and let someone else take hits for a while.