On the flip side, marginal complaints might make sense if you see the benefits of e-shifting as being marginal for your riding as well, especially given the inescapable non-marginal matter of cost.

There are some notable benefits to electronic shifting, but I actually think the most common arguments in favor of it are fairly weak, and generally blown way out of proportion. I can rapidly double-shift to bail myself smoothly between chainrings on modern mechanical STI just fine should a steep hill suddenly appear, and I have no issue shifting every few seconds.

IMO biggest benefit to electronic is that you can set things up so that shifting doesn't disrupt posture. The benefits are most dramatic on TT/Tri bikes; putting a second set of shifters on the base bars does for aerobars what STI did for drop bars decades ago. It's still quite nice on road bikes, although mechanical brifters already catch most of the low-hanging fruit compared with older systems (i.e. downtube or bar-end shifters).