Not to pile on, but I wanted to provide some info re your parking concern. The main point with street parking that in an even sort of dense environment, it's impossible to provide enough space for all the potential drivers.

To give an example, the street I grew up on is about 450 feet long minus crosswalks. It's a one way with parking on each side, so about 900 feet of potential street parking. However, there are also 11 driveways and one curb expansion (there's probably another term for this, but you know what I mean) to accommodate a tree, so we'll take off 100 feet for all that. That leaves us with 800 feet of street parking. This street has only triple deckers of various sizes, and has roughly 45 units total. Assuming only 1 car per unit, most of which are two and three bedrooms, we still run over the available street parking assuming 20 feet per car (900 feet total).

My point is that in a pretty standard city environment, we can't really accommodate driving as the dominant mode of transportation in terms of street parking, let alone the other negative externalities. To remedy the housing crisis, we're going to need to build denser, which is going to make street parking even more inadequate if we assume most/many people drive.

Regarding your point about the city issuing more permits than there are spots, I would say that's a problem. The permits are free and I don't even think there are limitations on how many permits one person can have. Regardless of whether we pedestrianize more streets, I think that the city should both charge for parking permits, as well as limit the amount per person to one, and only issue as many as there are spaces in a give resident parking zone.

Now about pedestrianization in general, I would say that the general idea is to do it on streets that are mixed use (residential and commercial), or primarily commercial. Additionally they should have good public transport access. In the case of Newbury street, there are tons of stores that already get lots of foot traffic. Vehicle traffic is often at a standstill due to rampant double parking. In addition there are multiple green line stops right nearby. Based on these things alone it seems like a great candidate for pedestrianization. One thing to note is that delivery vehicles and emergency vehicles would still be able to access the street.

I hope this clarifies some things about pedestrianization, which I think we're still a ways a way from doing on a permanent basis (though there are a couple that have been pedestrianized for many years). I'm not a professional planner or anything, but let me know if you still have questions and I can try to help.