I was always under the impression there were less just because you see less of them. But perhaps they just didnt get the stickers as often as the vans due to the van craze?
A mate of mine has just bought a HJ ute optioned as L31 M21. But it has 3 seat capacity so maybe more people needed 3 seats in utes for work so a Sandman was no good? Its a kingswood by the way.
As for utes being for tradesman I cant understand why they didnt but one tonners instead anyway. Utes are useless for carrying anything anyway.