The lack (or rather loss) of detail is something I've noticed too, especially when it comes to the re-working of
familar parts. To me, as toy lines go, one of the things that has traditionally put Lego a cut above the rest is the high quality of plastic, the clean molding, reverse-compatibility (of both part clutch and color) and detail.
One thing that I (and many others) have noticed in the last three to four years is the "translucence" and "waxiness" of some of the lighter colored plastics. For some reason, whenever I crack open a new set with any amount of red, yellow, white or lime, I can hold one of those pieces up to the light and see a significant amount of light pass through. If I take, say, a vintage (near-mint condition) yellow plate and hold it next to a newer yellow plate of the same type, there's a distinct contrast between the two in terms of translucence, with the older part admitting almost no light. I had hoped, with advent of SPIII, that Lego would have sorted this out by now, since the earlier SPIII sets had some good solid white parts mixed in with "Mars Mission milky white". But recently I bought the same set you bought, the
Undercover Cruiser, which comes with a pair of
curved fender shells. When held to light, one was nice and solid, and the other translucent. More than half the white in that set was milky, so I don't know what's going with their injection process these days... the consistency just doesn't seem right. Not to mention the molding (for some parts) just doesn't seem as clean.
I have sort of a love-hate relationship with stickers. On the one hand, as a customizer, I like having the option of leaving details off if I want to. On the other hand, stickers can be a pain to place, and placing stickers on textured roof bricks is sacrilege, IMO. I'm really disappointed in Lego not printing those, it seems uncharacteristically sloppy for them to do that. I know they're trying to cut costs, but stickered roof bricks would never have passed QA even five years ago.
I agree about a lack of controls in ships, which was especially bad in Mars Mission, but I do see some effort in SPIII to have controls of some kind (Hyperspeed Pursuit comes to mind). Atlantis has decent controls too. I'll also say to Lego's credit that most of the newer City cars have opening doors again, and Alien Conquest has
neat guns with some detail, so maybe they're trying to learn from their mistakes...
A key thing I've been noticing about the Lego of recent years vs. the 80s-90s is the level of realism. Oddly enough, it's the older sets of the 1980-1995 period that look more "realistic" to me than the current sets, which look more cartoony somehow. I think a lot of it has to do with the simple modularity of the older designs. If you look at recent airplane designs, for example, you see lots of pre-fab body sections and noses, things you would never have seen 20-25 years ago. I'd also like to see
the classic smiley in more current offerings, since he's kind of an icon for Lego. Come to think of it, the classic smiley is another of those things that looks more "realistic" to me than more recent head designs. I think it's the fact that you could look at that plain face and make up your own characters, imagine personalities for your figures. Now, the heads all have "angry" or "happy" or "confused", etc. expressions already printed on, which limits what those minifigs can be. Not that I don't like some of the newer faces, but I kind of prefer a more modular approach. Something more like the Pirate faces of the late 80s-early 90s. Those were basically just the classic smiley with an eye patch added (or stubble, or lipstick, whatever the case may have been). Interesting, yet still simple. A perfect balance of unity (the classic smiley) with variety (the eye patches, sunglasses, etc).
I think that's the magic that Lego always had for me growing up, and a quality I've been missing of late. Simplicity balanced with complexity. Make designs and parts just interesting enough to grab my attention, yet simple enough to be taken apart and made into something else. Perfect examples of this can be found anywhere from the classic space era all the way through to Blacktron II. Perhaps the word I'm looking for here is
elemental. A BURP is not elemental. Neither a big saw blade nor a big chunky drill piece is elemental. A sinister, gold-toothed grinning minifig head, fun as it may be, is not elemental. Technicky "gimmicks" and air pumps and rubber missiles are not elemental. Bricks are elemental. So are plates, wedges, sloped bricks, headlight bricks, cheese slopes, vents, etc. These are all things that can be used a million different ways, and hundreds of different ways within one set. That's what I want more of, and what classic space, town and castle (to name a few) had in abundance.
Not that it's all bad nowadays. Creator is a very bright spot in the current lineup, with a great part selection
and alternate designs being incouraged. Despite what I've said, I'm not ready to give up the hobby just yet.

I just wish Lego would take more inspiration from its own history, and not put the bottom line before it's traditional level of quality.