The big difference now IMO is that only bitcoin is rising, altcoins are still in bear mode and therefore they could not contribute to the total volume.
However, looking on the comparison from last 2017 and today's trading volume, I can say there's also an improvement because volume now is $54 billion
according to https://coinmarketcap.com/,
Alts have gone down during the last 2-3 days. Initially, they were also in the bull mode. Bitcoin dominance is now inching closer to the 55% mark, and I think if the trend continues then it may even rise to 65% or 70% by the end of this year. A part of the lag with regards to the alts may be due to the negative incidents surrounding BSV.