I mean yeah… getting cars into your city is like the whole point. Cars are filled with people and people work and spend money. Specifically outside money. This is a city that has no subway or rail, vehicles are the only means of moving people. If you rip out the parking you won't get a vibrant walkable downtown, people won't start taking the bus, demand rail or move downtown because "the downtown area" just isn't that valuable of a destination. You will get a dead downtown. In a sad twist of fate when your "business district" doesn't have the capacity to absorb workers commuting or people going out on nights and weekends you'll see commercial buildings spread out even more to areas that can. Little pockets of nightlife and office space crop up next to newly built 5 over 1 apartments with plenty of parking built adjacent to major suburbs.
> because "the downtown area" just isn't that valuable of a destination
This is another point people miss - 50 maybe 75 years ago the downtown area was a valuable destination because stores were smaller and what you needed could only be found at one or two places in a city; often downtown.
Cities are much bigger, but so are stores - you can go for months shopping nowhere but a SuperTarget or Walmart; and half the remainder can be delivered.
You make downtown desirable and then begin fixing the traffic problems. It takes 20+ years, but it can be done.
> Cars are filled with people and people work and spend money.
You're conflating people with cars. You want people and you're assuming that all those people must be attached to a car. There are other ways to get people to be populate an area which brings me to my second point...
> If you rip out the parking you won't get a vibrant walkable downtown
You will if you build a lot more housing in that area. If thousands more people are able to live right there then of course it'll become more vibrant. That parking garage could be home to hundreds of people. Instead it's temporary storage for cars. The problem is that suburbanites are going to fight tooth-and-nail to bring their cars. So what you get is cars.
If that's what you want, so be it. That doesn't sound like a vibrant place if everybody has to drive a car to get there, though. It's traffic by design.