The argument argument removing Dispensers is obvious, but I don't see the corresponding argument for Teleporters in the same light. Sure, there are larger maps where not having them utterly cripples your team's attack, but then there are others, including entire game modes, where teles do little to nothing. There's essentially no need for them on a KOTH or Arena map, and they're often largely useless on CTF. When you're defending the last point of a Payload or push-CP map, they won't do much good, since you're spawning right next to those points anyway. They're useful on 5-point CP, but if a point or two keep trading back and forth, an Engy can be hard-pressed to get them set up in the proper places quickly enough for them to make a difference. I'd say they're only truly indispensable on pure attack and while defending forward points. It'd be up to individual Engies in those situations to play smart and set their loadouts accordingly.
...not that your average random pub player is known for playing smart, but oh well.