While they are doubtless improving, the main factor in their acceptance is the fact that less and less musicians have ever used the amps these things are emulating. Remember back when people were serious about their music systems? You spent a ton on your Marantz, McIntosh, Dynaco, Acoustic Research, JBL, Wharfdale so you could hear the nuances and dynamics of your vinyl record collection. Now most people listen to overly compressed, digitally recorded and processed music on $10 earbuds or 3" computer speakers. Don't talk to me about how your Excellent 4000 DSP Deluxe amp sounds just like a whatever...most of you haven't even heard one, let alone played it and felt it interacting as an extension of your instrument. And yes, I sometimes gig with a Solid State amp because it's light, loud and tiny. But je me souviens.