Encounter design was not what I would have gone with. We where in a back alley behind the Yawning Portal Tavern, with a sewer separating us from the NPC Monsters. Only way across was down to the sewer (20 feet deep, 20 feet wide) or across a single 5 foot wide bridge.
That wasn't the only way across. Anyone who could teleport 3+ squares (mostly eladrin, I imagine) could have gotten across as well as anyone brave enough to jump onto the sewer pipe and then from there onto the other side.
Sometimes 4E is about thinking outside the box. After I saw both of our defenders fall into the drink, I wasn't about to chance that bridge.
Perhaps are DM missed that information (he was new as well). We had no checks on the bridge, and sewer pipe appeared to be 20 feet down as well. You are correct that an eladrin could have teleported, but we didn't have on in the party. A windsoul genasi could have flown, as well, but we didn't have one of those either.
Is that a small-sized subrace of Minotaur?Minitaur!

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.