If you're over 35 and your music sounds hip and is in line with the new generation's tastes, I feel sorry for you.
 
I'm not concerned about appealing to teenagers and people in their early 20's anymore than I factor in the tastes of toddlers. Technically, they're a minority - and they don't even pay for their music, anyway...
 
Obviously, there are exceptions.

Jeff Evans
If your music sounds dated it is probably because it is! It means your ideas are dated. It has nothing to do with the instruments involved.

 
While this is an OLD thread...... dated might be the proper word..... is it a pun of itself?  
 
No matter, always a relevant topic for songwriters and artists.....
 
Jeff nailed it..... It's not the instruments necessarily, but more likely how you are doing things, and thinking while writing and recording.
 
Two artists can record the same song.... one will sound dated and ordinary while the next might be contemporary and fresh..... yet still the same exact song.

SongCraft
Gid'day,

As the year comes to a close I have re-accessed my work, having contacts in the music biz and received feedback (catchy, melodic but a little old hat) and having posted my work on the CW Song forum for feedback I feel that most of the songs and instrumentals posted there are superb but 'old-hat' and also not to forget those great 'old' cover songs.  (no offense intended), I do love all those old classics.

I guess most of the works posted in the CW Song-Forum are mostly from older age groups? (40+),  I'm also 40+, but I don't want my songs to be labelled 'old-hat' don't get me wrong I love all the old stuff...Classic Orchestrations, Blues, Jazz, BBKing, Beatles, Eric Clapton, Rolling Stones, Led Zep, Jeff Beck, Pink Floyd, Metallica, (too many more bands to list), right up to current new bands!  Everything from Jazz, Rock, Pop Rock, Heavy Metal to Prog'House, Hip Hop, IDM and everything...

You realize that you stated that there is a very large market for (what you are told is) "old hat" in your second paragraph.