The CTA was planned for growth, but that planning occurred in the 1920's - it's simply outgrown its natural capacity, and there's really no where for it to grow...being so (over)used, it's got to be nearly impossible to keep it fully and properly maintained...
I wonder if there is some corruption in the CTA that keeps maintenance dollars away from maintenance and into something less constructive.
That "corruption" is called underfunding which, for the last decade or so, has required capital funding to be diverted to cover operating costs in order to preserve ever-deteriorating service (see also: Amtrak long-distance trains, mid 1990s-early 2000s).
The system is truly falling apart, and the different service boards of the RTA (CTA, Metra, and Pace) have repeatedly told the state that several billion dollars will be needed over the next few years (a few hundred million per year) to, essentially, bring the systems into a state of good repair. How did the state respond? By telling everyone that transit funding was "not on the radar screen" for this year, despite threats of massive service cuts and fare hikes by the end of this year if the boards are not able to close budget gaps (which would be up to $110 million for the year at CTA alone).
So now the state legislature has missed their target deadline for getting a budget passed (May 31), and those poor babies have to work overtime (but not too hard, though, because they've been taking four-day weekends) and are finally realizing that, maybe, transit should be on their radar screen. The most likely resolution will be a budget patch for this year, to prevent the service cuts, but no restructuring of the funding so that we can prevent a repeat of this drama in another couple of years.
While you can argue that some ventures may be foolish (Airport Express, anyone?), even taking that stuff out wouldn't come close to covering the overall needs of the system.