I was just about to quote that exact piece Tuor!
I believe that Ulmo was prudent - why not let the Eldar be alone to their own devices in Middle Earth. The correspondance between Valinor and Middle Earth could still be great, and much could still be taught and learned, without the need to live together. I believe Ulmo (and quite obviously Ossë) forsaw that problems would arise from the Eldar dwelling with the Ainur - if anything ever went wrong, they'd feel pent up and captive.
That said, Morgoth would still have come to power, and the problems (though maybe not as dragged out) would still have been very severe. There would have been no Silmarils to fight over, yet Morgoth would still have caused chaos. Perhaps some elves could have been swayed by the dark lord and a racial civil war forced to ensue anyway. Perhaps all the Elves could have been turned, and would have sailed off in war to Valinor.
The Valar in my opinion meddled overmuch in the doings of the Eldar... and though there was a lot of knowledge and wisdom exchanged, it came at a high price.