I think a lot of the digital remastering is hit or miss. It definitely has a lot to do with marketing, but some of it is sincere and done well. Unfortunately, labels can have something cleaned up, boost the treble, and compressed and many people will tend to prefer it to the older version when they compare the two. The compression can actually make a recording sound like it has more details too. It doesn't only squash the loud signals...it brings up the quiter signals, both musical and unmusical (sibilance, reverb, string noise, etc). That makes it hard to tell whether a remastered version has more detail because of original masters and modern 24 bit remastering equipment, or simply because the signal has been compressed and altered. It all depends on how poor the original release was, and how well the remastering was handled. There are definitely many remasters that were done by talented people, using original master tapes, and good equipment. I suppose your ears will tell you which are good and which are bad. Excessive compression and loss of dynamics *usually* makes a recording more grating and harder to listen to for long periods of time. The ones that you end up preferring and listening to for hours and hours are probably the ones that were mastered properly.
As far as Dire Straits releases go...I'm not sure how well the originals were done. If I remember correctly, wasn't their first album cut a little short on one song?? A premature fade, or something? The tape hiss issue could mean that it was digitally removed on the new version (which would mean that some musical signal was probably removed with it), or it could mean that they used a different set of master tapes...quiter originals versus a copy. THere are a lot of possibilities, but I do think you're probably right about the newer remaster being compressed more than the older release...it's definitely a trend.
As far as Dire Straits releases go...I'm not sure how well the originals were done. If I remember correctly, wasn't their first album cut a little short on one song?? A premature fade, or something? The tape hiss issue could mean that it was digitally removed on the new version (which would mean that some musical signal was probably removed with it), or it could mean that they used a different set of master tapes...quiter originals versus a copy. THere are a lot of possibilities, but I do think you're probably right about the newer remaster being compressed more than the older release...it's definitely a trend.