You can call it a "typical playground answer" if you want, but that doesn't change the fact that it's the *correct* answer. The project has a limited budget to work with, and paying someone to port and maintain X.509 certificate support simply didn't make the list. If a feature isn't being used by the vast majority of users, why divert effort from other areas?
Minor features get dropped all the time, especially when a project undergoes a large-scale rewrite. It's not "gratuitous", just matter of setting rational priorities. Conserving maintenance efforts by pruning disused features is a good software development practice, and, rose-tinted memories aside, it's not like Konqueror was ever a killer app for KDE in the first place. With most KDE users running Firefox or Chrom(ium) anyway, they would be foolish to waste scarce paid-developer resources on Konqueror. You can probably count the number of affected users on one hand--and like you, none of them are offering to do the necessary work.