Middle pickup can be handy too... Though I am not much of a strat user, I can give you some possible uses.
For one, if you set up all three pick ups about equally, you can get a moderate tone between the quacky neck pick-up and the biting treble pick up. As alpha1 suggested, too much of neck warmth can drown you out in the mix while too much of bridge bite can kill the warmth of the tone.
You can also set up the pickup with the treble side closer to the strings and the bass side further from the strings to give a higher treble emphasis for your chords, and tightening up the bass notes when you strum. This can be especially useful for funk rhythms. Or you could get a very low output pickup in the middle to contrast it with high output neck and bridge, as in an HSH config.
BTW, instead of using the middle pickup for noise cancellation only, you can upgrade to noiseless or active pickups and add more variety in your tones.
-- My current rig
Guitar: '98 MIJ Ibanez RG520 QS w EMG 81/60
Amp: Laney LC15R Tube, Fernandes 20W SS
Pedals: MI Audio Tube Zone Overdrive, Boss OD3, CS3, MT2, HM2, DS2, CE5, DD7, TU3, Beta Aivin DD2 Delay, Dunlop Crybaby 95Q, Stranger Vol Pedal, BBE SupaCharger
Others: Yamaha RBX 374 Bass, Yamaha MM-6 Synth, M-Audio Fast Track, Shure SM-57, Heet Sound E-Bow Plus
Wanted(pm if selling): EB VPJr/Boss FV500L,Ibanez w Original/Lo-Pro Edge