The reservists I worked with were a damn keen lot for the most part, albeit there were a few who made minimum commitment for the bonus qualification - but compare that the the regulars who are hanging around because of Boarding School Allowance etc, or do the minimum to avoid a bollocking, and I always thought the reservists had much better attitudes. They also had a whole cross section of civilian trades, life skills and were broadly less one-dimentional that regulars, proving to be quite resourceful when deployed...but by luck more than design or command planning.
What they do often lack is military experience, either in trade or fighting skills, as by definition they simply don't have the days available to train and exercise as much, so as was seen in 2003 they were handy bodies to guard stuff in Kuwait, but not much more. They're there to be led as opposed to being an instant 'just add war' ready-to-go force. Maybe as intended, but that doesn't look good on posters.
The reservsts that were more useful elsewhere had normally managed to commit to more days, and in one particular case I know of a tradesman who became very useful to his home base, augmenting their stretched manpower. But only because he was previously unemployed and had been on unit a while: aka...full time. QED.
It's a political money saver, not a sensible defence strategy. My 2c.