Well, I'm late to all this, but I reckon these changes could be a welcome change to honk-and-fly exploration. That was only even meant to be a placeholder system anyway, and it's a shame it's stayed as it is for so long.
I get the all the concerns that we might have to spend longer messing about to get a sense of whether planets are worth exploring, and that the new system will just be adding time to something that is already time consuming in other ways, but I'm not entirely sure that'll be so.
Depending on how well it's implemented, the histogram you get from the initial honk should be enough for an experienced explorer to tell whether the system contains exploration gold or if it's just a bunch of ice planet tosh. The same should apply for USS's too - if they're interesting phenomena, then they should emit more juicy readings on the histogram. We can only wait and see if this is the case.
There is the issue of bodies that are out of range of the initial honk/scan too. We've all seen systems with a secondary 500,000ls away which will be out of range of the initial scan, and we won't know if they even exist to fly out to discover. I don't think this is a bad thing. I love the idea that relatively well travelled systems might contain secrets that everyone else has missed. I think that could actually add a lot of what is missing from exploration.
Incidentally, as any OG explorer will tell you, there was a time when there were no discovery scanners at all, and even when they first appeared in the game, the advanced scanner was fabulously expensive by the economic standards of the time (well, for a week or so anyway). So how did we know what was out there? How did we find planets in all that black nothing? We used the Parallax Method.
Basically, you rotate your ship slowly on its point and watch for any "stars" that move separately to the starfield. Anything that stand out is in the system. Sure, it takes a lot more time to find these distant bodies, but that's how it should be. You do get better at it, and you develop a intuition as to where to look in a lot of cases. It's as much about situational awareness as anything else, and understanding anomalies on distant known orbits will help, so there's skill there too.
Exploration should never have been a one-click job and I've always missed that dead-eye, skill-based way of finding things that others might have missed.
Exploration has been more of a test of endurance than any real kind of skill for far too long, which is a shame. It's been about how many jumps you can stand to do, how many times you can open and close your system map, and how many times you can hear the honk before you start gibbering in your cockpit against the backdrop of infinity. There has never been an element of skill, born out of experience, that could minimise that implacable requirement for managing tedium.
These changes could do that. Getting good at reading the histograms, building up your efficiency with the Parallax Method, and generally learning how to be an actual explorer and not just a button presser and map opener are things that I'm looking forward to. Exploration has been missing the skill requirement for far too long.
Of course all this depends on how well the new system has been implemented. Hopefully the beta will last long enough for meaningful feedback to iron out any kinks.