I think that given the inherent scarcity of MVP-caliber talent (by definition there's really only ever 4-5 players at most in any given year who are near that level), it doesn't make sense to orient your team building strategy around acquiring that level of player.
I think it makes sense to try, if you can, to keep open the option of trying to pounce on whatever opportunity arises to acquire such a player. But those opportunities are exceedingly rare and the competition is inevitably fierce.
If you say, "Well we can't contend without an MVP so all of our efforts have to be focused on figuring out how to get one," you're going to spend 90% of your time as a franchise trying to get the guy, and very little of your time actually competing with the team you currently have. And we've seen in the past decade that once you get that guy, you may only have him for a season or two. So we're really supposed to spend 5-10 years at a time trying to get a guy just so the team can make a serious run or two before heading back into the wilderness?
It was a different matter back in the old days when a team that obtained a legitimate franchise player would be sure to have that guy for a decade or more. Spending a while searching for a centerpiece makes more sense in that context. Now it seems like teams are better off trying to create some stability and a culture that star players may be attracted to join.
I like where the Celts are at now. They've drafted and developed a young core with multiple All-Star level talents. They've cultivated a deep stable of assets / supporting pieces while keeping the cap sheet relatively clean long term. They have plenty of flexibility for molding the supporting cast around their core.
If a MVP type player becomes available, Ainge will have some options for trying to get in on that conversation. But if, as is always most likely, the Celts don't really have a chance to acquire a MVP player in his prime, they still have a team that can be among the best in the league for the near future.
I think the Raptors model is a good one to follow -- build a good team with solid infrastructure. Compete year after year. If you get lucky with matchups and your team gets hot, maybe you make a deep run. If not, you've still got a team your fans love to follow. Then, when a superstar becomes available, you can try to make a trade to go all-in, even if only for a season or two. Then when that guy leaves, you still have the infrastructure to fall back on so you aren't left totally high and dry.
I used to have a more all-or-nothing mindset about this stuff. I used to think that if a team isn't clearly in contention then the right move is to tank and accumulate assets until one of your young guys turns out to be the next big thing or you trade for "the guy." But now I think that way lies madness.
You can't just churn and churn and churn endlessly. Either your team will develop and end up being too good to keep drafting good players, or your team will stay bad in which case the whole thing will sour and your fans will get fed up. The last thing you want to be is the team that is constantly trying to sell its fans on the hope of the next free agency period. I think we've also seen that following "The Process" or some similar method, even when a lot of good luck is involved, doesn't necessarily put you in a better spot than other teams that followed a more middle of the road approach.