Radosław Szymczak thanks very much for your detailed comment! I agree that it's a work in progress. Please post/vote for these great suggestions on UserVoice, they really do listen to that! (https://sharepoint.uservoice.com/)
I also share your hope that they don't change direction again, and I'm feeling confident they will stay the course. The last time they redid the whole page structure was in 2002! Microsoft itself is building on SPFx with tons of web parts and whole modern page experience, and I think that's a sign of its longevity.
Regarding the "more secure" comment, if you figure out how to tell Joe E from Joe T, please let me know! Tripwire reports that insider threats are behind most security breeches (https://www.tripwire.com/state-of-security/security-data-protection/insider-threats-main-security-threat-2017/). Anyway, I know it's not perfect but it's certainly an improvement; in my (personal) opinion, the add-in model showed that a more secure approach was so cumbersome it stifled adoption. That's why I said "more secure" not "completely secure" ... it's all relative!
Thanks!