This chapter kind of glosses over limited depth SRS, so I'm going to explain why people sometimes choose that option. The main benefits of limited depth SRS are that you lower the risk of complications, recover from surgery far faster, and that you don't need to do any dilation. The main downside is of course that penetration is more or less impossible, since the cavity is only 1-2 inches deep. That is probably a deal breaker if you want to have sex with men, but if you're a lesbian penetration is not as important. Of course, there are some types of lesbian sex that involve penetration, e.g. sex toys, so its not an always the best choice, but its worth considering.
Limited depth is also somewhat popular with asexuals, since if you don't have sex, depth is not a priority. It still isn't an easy choice; even if you don't want sex, some aces prefer full-depth because it makes them feel more like cis-women. But that has to be weighed against the longer recovery times of full depth, and the frustration of needing to dilate. Dilating isn't fun for anyone, but if you aren't seeing the sexual benefits of depth, it can be particularly annoying.
One more thing to remember is that surgeons are often finding new techniques. For example there have recently been some human trials on a two-stage process, which if perfected might be a way for people to try limited depth, and if they don't like it to then have a second full-depth surgery later. So if you're considering SRS definitely do a lot of research into all of your options, and talk with your surgeon.