I'm not sure his range is wider now, well I certainly don't hear it. His voice in the 80s and early 90s showed real power, range, emotion etc. Bono's voice was one of the main reasons I started to like U2, just like many other powerful singers such as Freddie Mercury, Mike Patten, Chris Cornell, Eddie Vedder, it adds that extra dimension, it's take it to a higher level and makes the more more exciting.
There have been some great vocals by Bono in recent years such as as Magnificent, Fez-Being Born, but on the whole it doesn't sound as exciting, interesting or dynamic as it once was. You can't deny that listening to All I Want is You is much more satisfying than Crumbs from your table, Playboy Mansion, Original of the Species, Stuck in A Moment etc, all have decent vocals but nothing that stands out as outstanding.
His vocals might have been more raw in the 80s, but there was definitely more character and mystique, even so he has a better voice than many vocalists now, who sounds quite flat, boring and dull i.e. lead singers of Snow Patrol, The Killers, Coldplay are a perfect example, the tunes they make are okay, but they will never get to U2's level because they are held band by the limitations of their singers. Put 80s Bono into The Killers and they would be amazing for instance, their seems to be a dearth of really good, powerful singers at the moment.