I'm not sure it's silly. For me, preserving items like that is just as important as, say, a CCKW, Ferret, Landrover or anything else; and speaking as an engineer, just as if not more interesting. They all go to tell a story of how things - problem solving, design, development, engineering, working, soldiering, whatever - were done historically. I always think it's a shame that specialist commercial vehicles tend not to survive, and most of the vehicles you see at shows are flatbeds.
Having said that, I'm not sure our own collection has been particularly eclectic or insane, unless you count the bridging rig. I fancied a mobile aircraft control tower once (in fact twice - a Bedford TK at Aston Down, and the Karrier that used to be at Middle Wallop), and came close a couple of times to buying a Thornycroft LMD. At a miscellaneous sale I fancied an Access Equipment Ltd 'Beanstalk' - essentially an upright mounted, multi-stage hydraulic ram with a chair fitted to the top - but it went for a surprisingly large amount of money.
The best eccentric collection I've come across, however, has to be at Nothe Fort, Weymouth, though sadly it's not on display any more - a collection of military moustaches.