Great point(s) about the engineers; now your reputation with them and the amount and quality of your upgraded modules is it's own (just as?) important currency. I've finished off my run from mid level Tycoon to Elite in Trade since 2.1, but most of my time has been spent coming to grips with how to find materials efficiently.
Money for me is important to an extent because it allows me to play with any ship & outfit that I have a mind to, and I have no fear of the rebuy screen, but that is all; I'm far more invested in my engineer's status and my time spent flying to Beagle & back which made very little in the way of money compared to how many hours I put into the project. A lot of diverse goals for players in this game, and money is just one of them.
Absolutely. Engineers, post patch, is an extremely rewarding experience (warts and all). The few times it slips are when you're stuck trying to find material XYZ and RNGesus just isn't spawning it for you, as well as some of the crap surrounding the whole line to unlock Palin (Marco Qwent needs to die). I think having all the engineers at rank 5 (or whatever) has considerably more status than just being a billionaire (especially with that last community goal, lol).
Money is useful to get into the ship you want. Engineers make it YOUR ship. That feeling right there was worth what I paid for Horizons.