Q: "Why did they use segmented SRBs?"
A: Because Morton-Thiokol is in Utah, without a sea-port, and the pieces had to fit on trains or trucks.
Q: So why didn't they go with a company that did have ocean access, like Aerojet in Sacramento? A: James Feltcher was from Utah.
Actually, I think it's a problem that the anti-systemd forces keep going on about "the unix way" and what-not... haven't they been paying attention to the way things really work? (Hint: if esr says it, it's probably not quite right. )
Perl kicked Bourne butt by merging nearly everything you want into one process-- that's something you'd think a sysadmin would've noticed.
It is however a point that betting your system security on a new, gigantic project is kind of dubious, and I have a lot of sympathy with people objecting to gratuitious changes that obsolete decades worth of learning on how to manage a unix box.
 The actual "Unix Way" is "do one thing sort-of-okay and trick it out with options, configuration files and customization languages until you can't tell if it's going to fry eggs or go to the bathroom".
Yeah, I wouldn't say I'm up on the SystemD controversy, but I would've thought that was the whole point. The old-style of system startup fires off so many processes, I've often thought you might be able to speed up a laptop boot quite a bit if you just wrote one perl script that did all of that stuff. It could even use the existing rc.d mess as an input format, read it all in once, and stash the info in a sane, single-file format...