So I don't really have an opinion whether it's a good idea to do this or not, but don't think it matters much anyway because it is pretty easy to attack move some engies instead so this gives very little advantage or help to noobs anyway.
But from a technical perspective, could it be done by just automatically issuing an attack move order directly underneath idle engis? (and maybe have this order time out or only get implemented once a minute or something, so if there is nothing around to reclaim the engi doesn't continuously get new orders?)
You could make the argument it is helpful for some noobs but worse for better players because they want to know when their engis go idle and would be better off disabling the toggleable ability.
But in that case you could have the best of both worlds. It makes life a bit easier for noobs, but doesn't reduce the skill ceiling either. Otherwise, we'd have to accept the argument that attack moving engis AT ALL reduces the skill ceiling of the game and makes it worse, because manual reclaiming requires more clicking...and we all know the faster you click the more skilled you are, right? Sure, but just like including both attack moving engies and manual reclaim is perfectly fine, ADDING a less effective, easy option doesn't remove the skill ceiling. It is perfectly fine to allow some automation of tasks as long as there are also ways to do things more efficiently by micromanaging more.
So I'd say it just comes down to whether or not there is a reasonably easy technical solution that doesn't bog the game down much.