The problem is that the Doctor makes a really big effort to get them to come along with him... but then he never actually needs them. And it's not just that it turns out that they're (worse than) useless, it's that the Doctor never even attempts to make use of them.
They are used twice (positively):
* The Doctor uses their hand-scanner to pull Clara out of the echo of the console room
* They knock the Time Zombies off the bridge to let Clara and the Doctor escape - although they're then caught themselves.
Agreed. Unfortunately, that's mostly a commentary on how bad this season has been.
Given I really enjoyed Hide and The Bells of St John, that's an unwarranted statement.
This episode gave us great moments with the Doctor and Clara, explored the TARDIS, and gave more than one or two key plot points that will probably become very important later. (At least, I hope they will. If they don't, I'll be disappointed then). However, given that the Brothers have a faint recollection of what happened, and the Doctor probably more than that... and given the title of the final episode this season, what Clara saw in the library is good foreshadowing.