It doesn't make much difference whether you use Watts or Joules, since 1 Watt = 1 Joule per second, so both are just as convenient for electricity: 1 Watt = 1 Volt Amp, so 1 Joule = 1 Volt Amp Second = 1 Volt Coulomb (although amps seems to be more "normal" than coulombs).

It's a bit redundant to multiply power by time, when that's just an energy, but going between Watts and Joules is trivial (by design), so it's not too bad.

However, I can't think of a reason why hours would be easier to work with than seconds (as kiloseconds, if you want the same order of magnitude), especially regarding electricity?

Perhaps, but it makes conversion to and from an other domain than electricity a pain.