I usually agree with everything Buzzdraw says on 1911's. He's forgotten more than I will ever know about them. Where we disagree can mostly be chalked up to my OCD redefining "necessary", so caveat emptor for the rest of this post! LOLToday, with all the different models of 1911 out there, a user should be able to buy what they want, with all the features (saving grips) already on it. Most everyone has their own taste in 1911 grips and will swap factory originals out.
If you have to go changing out a bunch of parts (barrels, bushings, etc) immediately you bought the wrong 1911 and are afixin' to drop a bunch of cash unnecessarily.
I bought an ATI 1911 GI-E (the 4.25" gun), just to use it as an exercise in honing my skills as a gun plumber. It was dirt cheap and offered an interesting mix of enhanced vs. non-enhanced features. For about $300, I got to lower and flare the ejection port, undercut the trigger guard, bevel the magwell, do a bobtail conversion, modify a rear sight (open up and "U" notch one of the best non night sight factory fixed rear sights I've run across yet) and add a mix of internals and tuning to my preference. Stuff like adding a stronger recoil spring and EGW flat bottom firing pin stop to increase lock-up time so the gun stays flatter in recoil are a matter of personal preference. The only thing I changed that I didn't expect was the ejector, because the factory ejector broke at under 100 rounds. I chalk that up to a very weak factory recoil spring (yes I shot the gun before modding it). Sure I could've just bought a DW V-Bob for 300% more that what I've got in this exercise, but where's the fun in that? (OK, there's a LOT of fun in that, but it's a different kind of fun )
Another of my 1911's is a Colt Rail Gun I bought for competition. Obviously I changed out the sights, springs, added a magwell, grit tape and grips for better purchase, along with a few LW internals so the pig would "make weight". I swapped out the ambi safety for an STI because Colt managed to make the most oddly proportioned and uncomfortable ambi ever. Accuracy was fine out of the box so all I did was a little polishing and add a fully adjustable STI polymer trigger to make the trigger break and reset clean and crisp (no trigger rattle either), and it served me quite well. Sure I could've spent $1,500-1,800 for a custom tuned match 1911 out of the box, but I got the CRG for $800 used and saved $500-600 overall after mods.
I also bought a S&W 1911PD for carry while I was competing with the CRG. Other than cleaning up the hammer/sear surfaces and swapping in a matching STI trigger, the only niggle was it wasn't quite as accurate as the CRG. The lockup at the back was fine and I know Smith uses quality barrels, so I added an EGW angle bore bushing to tighten up the sloppy factory bushing fit. That tightened up the groups noticeably for just $20. So basically just trigger to match and bushing for that gun, which was also $800 used.
My DW PM-9 is the best "out of the box" factory 1911 I've ever had. Yet because it's for comp, I made changes to suit me. Spring tuning specifically for my match handloads to increase reliability and reduce recoil, a magwell for faster reloads, tuned the trigger to 2.5# and "glass rod" break. The same STI trigger for reset takeup, a thinner Dawson Precision FO front sight for distance accuracy at speed, and an STI ambi safety for off hand stages. A set of VZ Operator II grips finished out the mods and that is one incredible gun.
I've also done quite a few 1911 "fixes" over the years for guns that wouldn't run. 90% of the time I can trace it back to four basic 1911 issues. Those are magazines, extractor tuning and feedramp or chamber issues. Most 1911's will run just fine out of the box with quality factory ammo, but I always check extractor tension and engagement and where the rounds hit the feedramp to be sure. It's when you get into marginal operating conditions territory that issues tend to creep up. If your 1911 is properly set up and tuned to optimal parameters, it will work just as well as a Glock under adverse conditions, and look a lot prettier doing it. Most users will never need that, simply because they don't push the envelope when shooting. JMO, YMMV