Why do I need to purchase 2 ultimate game passes?

I have a similar question...so let me see if I get this right:

If I have a console w/Ultimate game pass, I can have multiple gamer tags /profiles on the same machine using the same game pass

but

If I have 2 consoles I cannot share Ultimate game pass between them because of licensing?

Correct.

Game Pass Ultimate includes Gold. If you purchase that, you do not need another subscription to play Forza with your friends. If you were to only purchase standard Game Pass, you would need Gold to play online with friends (and it would be cheaper to buy Ultimate anyway).

Do I need ultimate to play? Why Game Pass for Console exists then?

Gold lets you play online.

Game Pass gives you access to a game library so you can play games without having to purchase them and gives you discounts on those games if you decide you do want to purchase them to keep.

So they are 2 different subscriptions. You don't necessarily need either. If you do decide to keep both, I would suggest upgrading to Game Pass Ultimate. Ultimate includes Gold, Game Pass for the console, and Game Pass for PC and is cheaper than purchasing
Gold and Game Pass separately.

If you bought standard Game Pass and not Ultimate ,then it is working correctly. Gold is needed to play online. If you purchase Game Pass Ultimate, it includes a Gold subscription so you do not have to purchase it separately.

No. If you purchase just Xbox Game Pass, then you would need Xbox Game Pass Core (new name for Xbox Live Gold) to play online multiplayer. If you purchase Xbox Game Pass Ultimate, then it would cancel your Xbox Live and convert it to Game Pass Ultimate and add it on to your Game Pass Ultimate. Any remaining time will convert to Xbox Game Pass Ultimate time at a ratio of 3:2 and be rounded up to the next full day. For example, 90 days remaining of Xbox Game Pass Core or PC Game Pass will convert to 60 days of Xbox Game Pass Ultimate time.