You can't get the same degree of directivity. As wavelength decreases, you get more directivity for a given aperture. Light has 1/5000th the wavelength of plausible radio links, so both the sender and the receiver can have much higher gains. You also can have much more bandwidth, and thus you obtain many orders of magnitude higher data rates per unit of power used.

E.g. a 6cm telescope has 82dB of gain on each side for 1000nm light.

A 1 meter aperture (about what a 3.2x1.6x0.2m Starlink satellite can likely present to another satellite) has 53dB of gain on each side.

So for equivalent power, you have 6 orders of magnitude more signal strength, and you can occupy 10x the bandwidth, too, even if you have a very large phased array.

> The only reason you'd go for lasers here is thin civilian cover for developing a weapons platform.

This kind of system has very little in common with how I would build an anti-satellite laser system.