Timeless design (Swiss typography, Braun industrial design, Muller-Brockmann's grid system, Ando's architecture) - they're timeless because they don't follow trends or try to catch up with current fads - they're built from fundamentals and aesthetic sensibilities that appeal universally.
They look "outdated" because everything else around it is following current trends. You cannot ever say the Coca Cola logo is outdated, nor can you ever say the LOC logo by C&G&H is outdated. If anything else, it is advantageous to be constant and "outdated" (there are exceptions such as Fashion brands).
Regarding flexibility - I agree. But, most companies understand the value of their decades old brand - see recent tweaks of the Lufthansa logo, American Express or MasterCard - they tweak them for future compatibility and digital media. They don't just throw it out the window without good reason. "Outdatedness" is not a good reason.
