Too small for some species,yes,but in human perspective it can seem quite large.That's only due to the length though,as in reality it's just a long but narrow tank.It isn't surprising to me though,as I've heard of quite a few unhappy hamsters due to that size of tank
It's incredibly difficult to get tanks that are appropriate for the larger species of hamsters,and even then they're ridiculously expensive to the point where it just isn't worth it and you could make a bin setup with even more floor space for a fraction of the cost!