Umm I've been to Bletchley and NMOC twice and although the latter does have the particularly interesting live demos of the restored/recreated Colossus etc, it's completely wrong to say the "main" museum complex doesn't have much about the technical/crypto aspects.

If anything I'd say it's the other way around - there are exhibits on the way of life etc but the majority of them are on the cryptology and the approach the people working there took etc. I'm wondering if you accidentally missed one or two of the buildings.