When you have one terminal in space, and one on the ground you can greatly minimize the size weight and power required by the space terminal by increasing the size weight and power on the ground, where doing so is 'cheap'.

For instance, doubling the diameter of the ground terminal reduces the power the space terminal needs to transmit by a factor of 4.

Quadrupling the laser power on the ground allows the diameter of the space terminal by a factor of 2.

High power space-qualified lasers are NOT easy to find- I don't think any lasers of the type we need have been space-qualified for laser powers over 10 Watts.

So you can really offload a lot of the cost and difficulty by increasing the size and power of the terminal on the ground- where its easier.

For the relay you propose you would need to launch a pretty large telescope VERY far away...

We have demonstrated we can close a link even when the target is located ~3degrees away from the sun in the sky... the same restriction we have for RF.

Maybe with improved optical filter technology we can get even closer to the sun.

Yes, it would be nice to have such a relay, but it would be VERY expensive- we haven't even done it for RF communications yet.