This all has to do with planning and architecture. Non of what you say is by necessity true. A single spacecraft can be designed to both reach Mars and land there. I also disagree that there is an order of magnitude difference of difficulty between orbiting Mars and landing on Mars.

You're left with costs of similar order and complexity of similar order with a plan to not reaching a primary goal. This wouldn't fly politically at all.

If Scott couldn't come up with a reason to go to Mars I think he would be harder pressed to come up with a reason to almost go to Mars...

Reasons to go to Mars:

-Mars is an analog for Earth and has geology which could answer questions about climate theories concerning Earth.

-Mars again is an analog for Earth in weather with less complexity.

-Mars is a source of resources in space like the Moon, but with more of everything. There is water in the atmosphere to be extracted far easier than regolith process on the Moon.

-Going to Mars will build the infrastructure need to exploit space resources and will add to the knowledge base in ways incalculable.