When Summertime Saga gets to the level of completion that LSSB is at, it will probably be possible for it to have monthly updates, too. If I were DC, I would be reluctant to have frequent updates before the Tech Update is out because so much of the work will have to be done twice in order to adapt it to 1024x768 and 1920x1080 versions of the game.
Whether or not the Tech Update was a good idea, or should have taken this long, etc., is another set of arguments where reasonable people can disagree. It sucks when an update takes way longer than you expect, and other aspects of development have to be put on hold until the work is done. Every developer will experience it.
A monthly update cadence makes sense when patrons donate on a monthly basis. If DC is smart, he'll adopt such a cadence after the Tech Update. In the meantime, all anyone can do is cry about it.