It would be nice if there was an easier way to link to the interface without them creating an account but that’s sometimes not feasible.

It’s absolutely possible. Public measurements are available publicly (read: no login required) now via the new interface. To use your measurement ID for example:

https://atlas.ripe.net/measurements/1665596/#!seismograph

Note that the new measurement pages will replace the old ones in the new year, but until then both are available. They’re right next to each other in the navigation: old on the left, new on the right.