It's definitely an interesting option for schools with a need for larger computers that also have space for labs. For schools with smaller budgets and space constraints, it's hard to compete with Chromebooks for price and portability. It really comes down to the intended use: students working on graphics, game design, video, etc. will benefit greatly from iMacs; students learning typing and/or basic programming do well on Chromebooks.
The used to offer a few low-end options to schools that were not available in the regular Apple store. This iMac is probably just opening that up to the general public.