The main issue with the old Can of Worms was that mainline through traffic on 490 had to weave with mainline through traffic on 590 in a space of (IIRC) about 300 feet (in both directions).
Because of the way it was described to me as a kid (obviously, I wasn't around prior to 1987), I used to think it was a giant, paved intersection which was basically a free-for-all as to who went when. No ramps, no lane markings, no stoplight, no nothing, just a giant paved zone where you just weaved in the direction you wanted to go.

It was a major lightbulb moment for me when I saw an old visual and realized it was actually a set of directional-T intersections. So it was crazy, but not quite as crazy as the free-for-all I'd assumed!
Heck, the old Can of Worms was basically two closely-spaced Y interchanges with flyovers to allow access to Winton Road to/from the east and north thrown in. Judging by the satellite imagery, it's quite possible that every lane was an exit-only lane from the perspective of either 490 or 590. The current interchange had to sacrifice some connections (no more access from Blossom Rd to I-490, nor from Winton to NY 590 north).
If anything, I wish a few
more connections had been sacrificed, namely access from I-490 to Blossom Road, which creates the existing weave which wreaks havoc with afternoon traffic flow.
Here's a page about the interchange with a historic visual that I enjoy studying. The redesign must have been incredible to witness, with
everything changing. I-490 East to I-590 South is literally the only movement (including through movements) that has any similarity to its previous configuration.