I can only assume that they make more money from other products eg beauty, techie stuff, clothes etc. at those times.
We do seem to be getting a craft TSV every other week at the moment, so even if you are not interested in the TSV itself, it does mean that we get some craft shows in the evenings. Hopefully you get to watch some of those. Personally I get more of a chance to watch after about 8pm as little ones are in bed and the big one has been fed. Not sure if I would be able to sit down for very long at the w/e, however everybody has different demands on their time and it would be nice for shows to occasionally be aired at different times.