I have noticed the hot trend right now with rappers is that all of them are riding and attacking beats the exact same way and only picking tracks that already go with their voices/ styles. Now it can be a useful technique in the artist's arsenal but by no means should it be the only, or even main trick in my opinion.
Let's looks at some of the popular artists of today. T.I. for one uses hardly any similes and metaphors. Yet he is considered decently lyrical by today's hip-hop standards.
His verse wasn't the most lyrical but sonically it fit in well with the beat. Ludacris on the other hand, is extremely clever and is able to both ride the beat and come with clever lyrics to support.
Now I am not trying to insinuate that an artist has to go against the beat in order to have hot lyrics. I think Luda is evidence of that, however, we have gotten to a point where all you have to do is "not disturb" the beat and people are hailing your greatness. Even some of the greats can get tripped up by attempts to ride the beat too much.
I am always going to be a fan of lyrics and I take every aspect into consideration but as long as these artists are ignoring the actual words and just focusing on their delivery a la Tupac, I am going to be disappointed.