The business strategy is probably the problem. E.g. Nintendo may have a policy of never letting their core ip’s be developed by a 3rd party. Financially the timing may be incorrect, so they are not ready to pump more money into developing a campaign or they might have wanted someone else to do the game on cheaper terms (after all, a few months with a small team and it’s done). There’s also a human issue too, companies often don’t like someone else in control of their development, they might have had any infinite number of political reasons not to release that game and often companies are inflexible enough to take a good opportunity and run with it. In the case of Nintendo especially, the implementation may not be what they want. Any remake is going to involve a choice of artistic styles, feel, control and intent.
Finally they are also obliged to give you an answer, even if they are not sure, because if they don’t, their ip rights are weakened by letting the game continue to exist if they don’t license it. So a no is the safe bet for anyone who isn’t directly responsible for generating profits – i.e. the intern who is tasked with pre-assessing pitches.
So it’s a gamble from your point of view, but the worst that can happen is you get a no and the eye of sauran watching your "reimplementation" of the game as a new ip. You also have a good demo in your pocket. The best is you may very well get accepted as a means to a quick buck and you get cut a good deal – royalty rights are probably unlikely but worth having a shot at – and you become a brazillionaire.