Just my few cent:
As far as development goes, unless there is insider information, everything we talk about is speculation.
Snow Daze is one of the highest quality finished product that was released this year, as long as it takes Snow Daze has less content than Summertime Saga. Maybe our expectation on the speed of which contents are delivered had overreached a bit.
That said, I do think there are a few aspects of SS that are unnecessary and time-consuming. First the mini-game, this is probably one of the aspect I find completely unnecessary considering what we want out of this game. Mini-games take time to make, it takes the artist's time to draw art for the games, it takes the progarmmer's time to write the logic, integrate the game, and debug. The development of mini-games are stacked on top of what we actually want, scenes and story. The worse part is, once the game gets big enough, it is possible for the codes of minigames to be a hinderance in stacking new contents when it comes to debugging. The more mini-games there are, the more scenes which depends on stats provided from these mini-games, the more future debugging maybe necessary, the more time it consumes.
Second, the large cast and the problems it brings. Snow Daze has five characters, and it still takes as long as it did to finsh, SS has...well I don't have time to count. I understand that each character probably has enough people that like them to justify their existence, but the large cast directly cause contents updates to spread out. We would have way more content on the main story by now if the cast was just 6-7. (This problem now is unsolveable anyway. Characters are introduced, and DC should carry on, but I just hope he would not add more)
There are many western lewd artist roaming around pixiv, twitter, deviantart, tumblr, itch.io, etc. I do believe that DC can find a willing compatible artist to work with him, I do not know how many artist he had contacted and what are their rates working in a project like this, so lets keep my comment as it is.
This industry in the west is still small, in Japan where this industry is established with well known and experienced companies and artist, a game like Rance X still took around 4-5 years to complete with delay. If an experienced company like Alicesoft took this long to finish Rance X, I wonder how long this game will take to finish, considering that DC might not have the expertises to tackle everything in a project that usually spread around several employees.