There are good current authors!
Brian Aldiss was a great, no question. But there are many good and very interesting current Science Fiction writers, although it seems that one has to look much harder to find interesting stuff than in my youth when I began reading SF with E. E. Doc Smith.
Part of the challenge is that the "Future isn't what it was cracked up to be" which is to say that convincing extrapolation has been slow to emerge from our current starting point. Gibson was great for the 80's but seems somewhat distant from today's reality, much in the way that the great space opera's of the 50's now seem more like fantasy than SF. Gibson really influenced several generations of writers, game producers, and movie makers with his dystopic vision for the world, but a lot of the assumptions don't ring as true for me as they used to. For some stimulating present day extrapolations try David Brin, Greg Bear, Neal Stephenson, Cory Doctorow, or China Miéville.