There is actually nothing that is better with roof's they are slimmer and longer.
For a long time only the best companys could produce somewhat decent roof's as the tolerances inside is much tighter on a roof prisms binocular than a porro.
Personally I prefer porro prisms.
Mostly people belive that roof prisms is more "modern" but i belive they are more popular due to fashion and personal preferences.
First binocular produced with roof prism was a Hensoldt from the first years of the last century, Zeiss had a patent for producing binoculars with wider objectives than oculars due to a wish to enhanced stereoscopic view.
So for decades the roof construction was the trademark of Hensoldt, and Zeiss did not produce the classic roof prism binocular before the closed down the production in Oberkochen and renamed the Hensoldt products with Zeiss in the early 70th.
That said the roof is not bad, not at all, its a great invention, but personally I prefer porros.
(but my favorite spottingscope is a roof)