Assuming markets are relatively efficient, it's a good thing that landlords leave lots vacant -- they're waiting for a future higher-paying tenant who can afford to pay the higher rent because they'll provide more value to their customers -- and these landlords are paying through the nose in lost rent while making that bet.
This ensures there's space ready-to-go for the expensive wine bar customers would prefer over the cheap cafe that would otherwise already be occupying it, or the luxury bakery over the dollar store -- and just like anywhere in a capitalistic system, we assume that the store that produces the most profit (and therefore can afford the highest rent) deserves the storefront, because this is the best use/value for those potential customers.
At the same time, I'm ready to rip my hair out over another favorite shop being replaced by yet another Duane Reade pharmacy or Bank of America branch. But you know who I blame? The customers, not the landlords. As depressing as it is, it's clear people in that neighborhood will now pay more for the convenience of banking and aisles of toilet paper than the old stores, and so be it.
Which is why, for the first time, I'm moving from Manhattan to Brooklyn. Which is fine -- in my eyes, parts of Manhattan may be getting worse, but parts of Brooklyn are only getting better. Neighborhoods aren't supposed to stay the same. I'm not going to lament a lost New York, when a new one is always forming!