Wnen Kennedy made his speech in 1961, the Moon was something doable within 10 years, even if the human space experience was only 15 minutes, at the time.
Testing the rockets and the spacecraft was possible in a quick tempo because the flights didn't need to last more than 2 weeks. So, it was possible to gradually test the systems and make a number of flights before the big one. It was also possible to make more flights on the Moon than just one. And also, the public's attention lasts a timeframe not longer than 2 weeks (that's also why most organized vacation trips last about 1 to 2 weeks).

But for Mars, there's a very different issue!
Before the first landing on Mars can take place, a test flight will have to be done, lasting the entire duration of a flight to and back from Mars.
This will take...3 years. And the crew designed for the first Mars landing will have to wait a long time before everything is considered safe and start its own flight.
And if (to save money) the same spacecraft is used for the testing as for the first Mars Mission, the aging of the spacecraft will have to be considered. Also, the public attention won't be the same during the flight. But this is more likely to tke place if it's a footprints and flag trip.
However, if the purpose is to stay on Mars, there will still be a first flight with all kinds of things to learn from before we can return back.
This is why I believe missions meant to have humans stay on Mars, with a basis, will need to wait until a very different propulsion method is designed and flown. The number of flights to and from Mars as well as their frequency will have to be far superior than what is possible today with chemical propulsion. Faster and frequent flight will mean better ways to correct what went wrong earlier. Otherwise we'd have to wait far too long with all the inherent problems linked to time.

Raoul