They won't always be....
Modern coins will not always be modern.
Every coin, has at some point, been modern. Time will tell which coins will hold or increase in value. Even in terms of "modern" coins, a few examples out perform others. Take a look at the 1999 Silver Delaware State Quarter - a steal at anything less than the Numismedia value of $3750 (last time I looked, anyway). Even the 2009 Lincolns, proof and mint state at collector grades, have, so far, outpaced other Lincolns of modern dates.
So don't be discouraged. Acquire them while they are cheap and just hold on to them for the long term. Their intrinsic value may just suprise you one day.