If you go by the Frontier lore (Frontier: Elite II in this case), most ship types (if not all) that exist in the ED universe should be capable of atmospheric flight.
It did require atmospheric shields though, if I remember correctly. So basically using a module slot.
Considering how much brute power most ships normal space engines have, meaning they can effortlessly hurtle big ship up even in 9g monster worlds, and how limited speeds are in normal flight (for most ships around what is achiavable by modern military aircraft) I don't see any reason to limit ships performance in most atmospheric worlds.
You could land without atmospheric shielding if you were slow and careful.
But that took a long time and had to be done manually as the Autopilot would kill you.
Also featured in Elite 2: Frontier, yes. The autopilot always went for the straightest path between you and your destination, regardless of there being a planet there. Sometimes it could get there if you set time acceleration to max, but other times you just got an explosion and the Game Over screen.Well at least Frontier: First Encounters Autopilot could kill you in various ways. Sometimes by trying to ram your ship through the planetMurderous suicide pilot....
Morbad, I consider many of those super dense atmosphere worlds flukes of Stellar Forge. Some of them have surface pressures on par with major gas giant core....
Off course if we have some kind of atmospheric flight dynamics local surface pressure should affect ships handling. But for Earth likes, Mars likes and such effects would be pretty negligible in speeds with ED's "normal space" flight.
It's hard to evaluate the overall accuracy of the bodies generated by the Stellar Forge, but we do know that there are a lot of terrestrial worlds ('super-Earths') out there that almost certainly have far much atmospheric pressure than Earth. Many of those past a few Earth masses are likely gas-giants with rocky cores, or would-be gas giants that have lost most of their atmosphere, but even many that are below that threshold would still be able to retain atmospheres with dozen or hundreds of times the density of Earth's.
Sure, at one atmosphere or less, the effects on most of our ships would likely be pretty mild, but I would expect to be able to land on Venus, or any of a billion other worlds vaguely like it, where a gentle breeze is like a tidal wave and ships at full thrust are slowed to a few tens of meters per second. Given all the time they've spent talking about it, I would also eventually expect to be able to enter the atmospheres of gas-giants, even if the surface cannot be reached. The seas of water worlds shouldn't be inaccessible either, and the distinction between a sea and a thicker atmosphere would be academic in many cases.