I doesn't look modern. Modern is what the Koerner-prise looks like (for better or worse). Modern is what the parts of the Enterprise in the teaser look like. The original design, because of the lack of details and 'simplicity' does look dated. No-one (even Matt Jefferies) would design the Enterprise in the same way again today - even if they used the same general layout. The best example of this is Jefferies refit from Phase II which became the movie-era Enterprise (the version of the Enterprise that still has to be surpassed as a design, IMO).