David,
Good questions. From a local person's view here is how I would answer them.
I personally don't love the course. There are a few holes that I think are really standouts, but the course overall doesn't inspire that type of response. I don't know that it could host a major for a multitude of reasons, but I think it would be a good host for a Senior level major like it hosted with the US Senior Open. I don't know that it is enough of a challenge or adequate infrastructure wise without some real trickery on either front for the regular PGA again or the US Open.
I have seen the course over three decades and it has changed in several ways but still maintains the overall tone. I think the look of the course was better back prior to the Daly-PGA event, but I think the course is in better condition and is perhaps tougher than it was then. Overall, I liked it better back then, but I think it is a fine line and a matter of opinion only.
I guess greatness depends on your definition. We are talking about a course that is continually ranked among the top 100 in the nation. It is often cited as one of Pete's best courses by him and other people that have studied his career. It continues to stay relevant on the top level of golf by hosting events like the BMW, Senior Open, and Solheim Cup. If those things don't put in the conversation of being "great" then you have a tougher standard to meet than most. Is it the best course in the Midwest, no. But the best in Indy or Indiana, possibly.
Is it the best in Indy? I haven't seen Wolf Run, so I can't comment on that one, but I have seen everything else worth considering at some point in my travels around town and I would say yes. Is the gap as great as many would lead you to believe? No. There has been a lot of quality golf built in Indy since the 1980s and places like Sagamore, Wolf Run, and Bridgewater really provided some other examples of solid design to the private clubs in town. The public courses like Trophy Club, Prairie View, The Fort, Prugatory, etc have really upped the level of golf on the public side to where any of those courses can be compared to some place like Crooked Stick and not be laughed at. I guess in summary you could say that perhaps Crooked Stick is the best known course in Indy, but there are several other courses around the metro area that are worthy of being seen.