The question of how feasible it would be to incorporate this feature, I would argue, is to a certain extent dependent on the design of a typical spacecraft in the context that we're talking about. Now if we move to the Star Wars universe, where most spacecraft seem to have awesome capabilities in terms of acceleration, one could assume that the typical spacecraft would already have sufficient engines to be able to make a planetary landing. Thus, the challenge of the gravity well is negated. In Star Trek, where starships are considerably less powerful, this becomes more of a point. in Star Wars, at any rate, all you would have to worry about, theoretically, would be aerodynamics, heat shielding and landing gear, and from the appearance of their spacecraft, it doesn't even look like they worry about that much, but instead rely on their shielding systems to deal with atmospheric friction. In Star Trek, shielding is presumably good enough to handle re-entry as well, since we've seen the original Enterprise operating at moderate altitudes on Earth, and clearly that ship's hull is less than optimal in terms of aerodynamics.You're thinking strictly in terms of feature set, and not in terms of the practical nuts-and-bolts design decisions that have to be made in order to make this possible. In order to design a spacecraft to withstand ground landings, you must make massive changes to its structure. You also have to deal with the fact that you are wasting huge amounts of energy dropping an entire ship into a gravity well and then raising it out again when you really only need to move a tiny fraction of that ship's mass. These design changes cannot realistically be inconsequential, nor can they be without cost and compromise to the core function of the ship. Any time you add a feature within a spaceframe of a given size and cost, you must compromise something else, and this is no small feature.
So clearly, in the Star Trek universe, the question shifts to one of how powerful their propulsion systems are. If the impulse engines of the "typical" Federation starship are not powerful enough to propel that starship from the surface to an orbit of an Earth-type planet, then I would agree with your above point. If they are, however, bearing in mind the well-demonstrated ability of standard Federation shielding to withstand re-entry and atmospheric friction, I would argue that compromises needed to adapt certain types of specialized starships for planetary landings would be "worth it." The design challenges would primarily be in terms of arriving at the optimal configuration to allow for easy landing and efficient loading and unloading of cargo.
If you take ST-style shielding or powerful engines out of the equation, however, then the feasibility of planetary landings for large spacecraft is obviously reduced.
That's perfectly valid. However, ultimately, the question becomes, is it worth the cost of compromised performance and increased manufacturing costs to have a single starship be able to carry a payload from the surface of one planet to the surface of another, without needing the services of a docking station and/or a flotilla of shuttlecraft. In my previous post I outlined three applications for this approach (and one can easily think of others where it could have some use), so I would argue that the question is ultimately whether or not its economically and technically feasible to create a dedicated spacecraft for those purposes.It's not just a safety issue; it's a "jack of all trades, master of none" issue. Dilution of design goals is historically one of the biggest blunders typically made by managers in charge of an engineering project, and the ability to land the entire ship is a design goal which works directly against other design goals such as maximum efficiency for space travel and combat.
Performance is relevant in the context of looking at how well a specific design is meeting its objectives. Thus, the shift away from companies talking about how technically excellent their products are, towards how those products help the buyer accomplish their objectives.Sci-fi is chock-a-block with "jack of all trades" designs or "jack of all trades" weapons, and I find it both tiresome and unrealistic. When performance is king, you need to specialize. Nobody is out there trying to build a race car which doubles as a stretch limousine, despite the fact that you could probably think of many uses for this feature.
Also, while a limousine doubling as a race car is an amusing take on compromised design, I would point out the recent spate of "crossover" vehicles which are designed to combine the best aspects of different classes of automobiles into a single product. You have cars and SUVs fused in products like the Ford Edge, and you have sports cars and luxury cars fused in the growing category of four-door coupes. Then there's the Maybach, which (according to one of their spokesman during the unveiling in 2002) could outperform some Ferraris with its 12 cylinder engine, but which is otherwise one of the largest and most luxurious passenger cars on the market. And I did once see a Masserati stretch limo being driven through downtown Burbank...
So in general while I agree with you that seriously compromising a design to achieve planetary landings would be a bad idea, I think that quite possibly, given the level of technology in Star Trek, and certainly given the apparent level of sophistication of Star Wars spacecraft, that in those environments, the level of compromise would not be serious.
