If you're planning on retiring before age 59½ you might compare early withdrawal options between the 401(k) and an IRA. It's been a while since I've reviewed the specifics, but you can start taking money out of your last 401(k) at 55 if you're retired. With an IRA you can start taking money with the 72(t) exemption, which in short means you take substantially equal periodic payments at least until 59½, but there are penalties for running out of money or changing payments.
IRAs have mandatory minimum distributions after age 70½, but I don't recall if a 401(k) has any such requirement. I may be wrong here, but I think Roth IRAs have the same RMDs, but it's not generally a concern since the money is already taxed, where withdrawals from a traditional IRA is a taxable event.
Last I checked you could roll a 401(k) into a new company's 401(k) or to/from a rollover IRA (but the money has to move direct from institution to institution, not through you else they'll withhold 20%).
Two or three time's I've rolled a 401(k) into a Vanguard rollover IRA. I feel like I have more options and control. Two of my rollovers were from a Vanguard 401(k), so assets were moved "in-kind" meaning no assets had to be sold or bought.
And I may have missed the point of your original post, but if so it won't have been the first time. Within my rollover IRAs I can buy and sell Vanguard funds, and if I wanted to I could open a brokerage account and trade individual securities inside the IRA. Since my 401(k) was with Vanguard there was no change in my AA or even fund investments when moving to an IRA.