You hate when people expect an attraction to operate in show-ready condition? Once upon a time, show quality was held so highly by the company that most rides were designed to shut down if certain show elements broke (and wouldn't be allowed to continue operating until it was corrected). These were again standards set by Disney themselves, not at all unrealistic expectations from fans.
A lot of what is wrong with Splash Mountain could have easily been prevented with just proper overnight maintenance. A decade or more ago, it's well known that Disney did away with many of the overnight maintenance crews that would go around and repair broken elements on rides and even touching up paint and replacing lights. It was even a company policy prior to the mid-late 90's to have a special crew go around every single night with a big box of light bulbs and replace any light bulbs that had reached 80% of their life expectancy (they didn't wait for them to burn out, so the only ones you'd ever see burned out were defective and had died early, and were generally replaced overnight).
Prior to about 1995 or so, the parks were kept in such pristine condition that they looked virtually brand new. You had annual refurbs for rides as well, but a huge amount of work was often done to them overnight to prevent problems from cropping up in the first place. Overnight and annual maintenance have been scaled back if not almost entirely eliminated and the result is blatantly clear.
It has gotten so bad that some elements aren't even broken at all- Disney just deliberately disables them to pinch pennies.
Another issue with why Splash is in the dire state it's in now- the last several lengthy refurbs haven't really addressed anything of importance at all. A couple of years ago (beginning of 2011 I believe it was), Splash closed for a month or so to install lap bars on the boats. Throughout this refurb, nothing about the show quality or mountain structure was addressed whatsoever, they completely squandered all the time the ride was down that could have gone towards fixing things. And things have gone downhill from there.
A decade or more ago, you didn't have EMH's and park hours that were 8AM to 3AM, and also a decade or more ago Splash was under 10 years old. As these attractions get older there is only so much you can do overnight. Change a light bulb, replace a speaker yeah probably, but replace an airline to an animatronic? no way. I am not defending mediocrity, but you have to take a realistic approach to this. You point out that on a previous refurb little was done cosmetically, fine. But under the hood everything from pumps to pipes to fire alarms were updated, replaced, upgraded. Stuff you can't see but is still just as important if not more so than a malfunctioning animatronic.
Does it make good business sense to divert all of your resources to keeping everything at 100% or have an acceptable level of show quality while allowing resources to be there for new attractions. Just remember, once upon a time in the 80's and 90's TDO didn't have to worry about some weird person named Harry Potter or an Island of Adventure.