I would lik to see discoverable planetary atmosphere so that colonization levels for colonizeable bodies appears only after survey.
In theory you get a general value XX.XX (Assuming temperature, atmo, and water value is for instance 0), and after survey you get the actual data which will result in the proper and correct details.
Function could be flagged at start. Something like: advanced exploration on or off.
I think the problem will be similar to that of checking every thermal contact. While this might be interesting the first few times, the tenth time, or the hundredth time might get a little tedious.
Right now, there are certain planet types (a combination of size, atmosphere and temp) that are more likely to have have spoilers that fire first and ask questions later. Therefore, you either approach them carefully, or send a probe, or maybe a scout shuttle. If you remove atmosphere information (for example), all that does is expand the number of planets where you have to be careful. So now, you either have the tedium of launching a lot more probes, or shuttles, or you risk losing an expensive survey ship because you can't be bothered with all the extra micromanagement. So then, rather than take that risk, you probably start using a swarm of less expensive survey ships to avoid too much of a loss in a single incident and interesting decisions are removed, because the mechanics are now sending you down an particular path.
Also, we can detect atmosphere right now at light years of distance, so it doesn't seem realistic to eliminate that information, when you can detect any kilometre-sized rock within a light year.
In v2.6, there are going to be more inhabited NPR bodies - due to the multi-system setup - so exploration will be more eventful anyway. I am certainly discovering that right now in my test campaign. I'll post an AAR when I get time.