"I've long suspected that this is largely because most politicians are selfish creatures that never see further ahead than the next election" - thats the old school - the curretn lot can only see to tomorrows media headlines.
Hard to blame people for taking a "peace dividend" after the fall of the Soviet Union - like the post WW1 "10 year rule". In both cases the old enemy WAS quiet for well over 10 years - the problem is having to suddenly say "we need to re-arm" after a long period of peace and no visible threat