If we had the opportunity to set unlimited at specific points (such as an intense scene with heavy use of particles, a boss etc) and then switch it off again in the more sedate places (menus, normal gameplay) then we'd get the best of both worlds and we (the developers) would be responsible for any issues that might arise.
As far as I see it, there are plenty of other ways we can break our own games with the tools Construct already provides and I think it's better for us (the developers) to decide what happens in our own games rather than you guys.
Maybe if the unlimited mode had never been put there in the first place I wouldn't be saying this, but it sure is tempting to use (if we could) in certain situations. If we cant' really use it I don't really understand why it's there at all.