In my view it is a problem, but one that can be worked around. The problem is that there is no large parking garage close to Ryan Field as one finds near most college stadiums. I think the school has made good faith efforts to build a parking garage near Ryan Field but the City of Evanston has been uncooperative. Work arounds include getting to the games early and finding locations outside of half a mile where there is free street parking assuming even then you can still find an open space (lots of no parking signs on the streets close to the stadium), paying nearby residents $20 or more for the privilege of parking on their lawns (though forget that strategy as game time approaches since the lawns are packed by 30 minutes prior), or again getting to campus early and parking in one of the campus lots and then taking the free, but usually stuffed (meaning you will need to keep waiting and waiting for one with seats), shuttle buses.
Not sure if it is still available, but there used to be a park and ride lot up at the Linden "L" stop that one can park in for a reasonable fee and then either take the "L" to the Central Street station and/or walk the 3/4 or so mile distance to and/or from the stadium. Maybe the fee is no longer reasonable on game days or the "secret" has gotten out by now so that it too gets filled up early.
I have tried all of the above except that I have observed, rather than rode, the shuttle buses as they kept passing by waiting riders due to being stuffed. When at a hotel in downtown Evanston I prefer riding the "L" from the Davis Street Station to the Central Street Station and walking from there to the stadium.
Since the nonstop Alaska Airlines flights from Anchorage to O"Hare arrives early in the morning, I can sometimes make it to a Saturday game without having to miss a day of work. For last year's homecoming that worked out OK until we arrived and then there was a snafu at the gate that delayed our getting off the plane. Missing the exit to the Tollway north didn't help any though my car finally reached Ryan Field as the game was starting. There were no open spaces on any of the even distant streets, and all of the resident lawns were packed. By sheer luck a business off of Central was able to accommodate me by opening up an extra space on their premises even though it required blocking several other cars. Of course even if Northwestern had a parking garage close to Ryan Field, it probably would have been full buy that time as well. The takeaway is that if you want to find parking near the stadium, the earlier you can arrive the better.