My mom sometimes says she never lied to us growing up. That's a lie.
Parents tell kids all kinds of lies to make them feel better. I didn't get to be tall until late in high school, which frustrated me a lot. My favorite lie she told was when she told me it was good to be short. I forget which tantrum I was throwing: not being able to ride a roller coaster or being bad at sports or getting lost in a crowd. Whatever it was, my mother said, "It's so much better to be short-- you never have to worry about your knees hitting the seat in front of you!"
This short-circuited my young brain. Now, as an adult who sometimes has to contort into a small backseat, I am more sympathetic to her wisdom.
It turns out, that in bridge as in life, there are circumstances where it's good to be short and also times when it's not good.
First--let's cover a basic principle. Ruffing isn't good in and of itself. Rather, ruffing is good because it can stop you from having side losers AND because you can gain an extra trick by ruffing.
How?
Let's look at the trump holding :
|
Dummy
|
|
Declarer
|
You start with 5 trump tricks. If you have a void as declarer and ruff something, you don't gain a trick. After you ruff with the 
10, you'll only take four more trump tricks (you only have four left in the long hand). If you ruff in dummy, on the other hand, you will still have all of your trumps in the long hand so you get 5 + 1. Ruff twice in dummy and you can take 7 trump tricks. That's the reason we like shortness, but notice how it doesn't work for the long trump hand.
You, South, hold
A109843 
A43 
7 
K83
Here are two auctions for you where your partner has invitational values:
A)
| West | North | East | South |
|---|---|---|---|
| 1 |
|||
| Pass | 1NT | Pass | 2 |
| Pass | 3 |
Pass | ? |
B)
| West | North | East | South |
|---|---|---|---|
| 1 |
|||
| Pass | 3* |
Pass | ? |
*Natural and Invitational
In both of these auctions, partner has invited game. In A, you have at least an 8-card spade fit. In B, you have a 9-card heart fit. Should you accept one, both, or neither invitation? B is clear-- bid 4. Your singleton is going to be very helpful for partner and maybe partner can set up spades. In A-- it's not so clear. You might accept. I would pass.
With singletons, remember that the longer your fit is, the better it is to have shortness. Similarly, having shortness in partner's suit is BAD. Look at this hand:
KQ32 AK7643 KQ3
If partner opens, not vulnerable, 2 in first seat, what's your call?
I'll take my chances and bid 6. The void is powerful, you have a big fit. If partner has Axxxxx of spades and two diamonds, you are virtually cold.
What if partner opens 2 in the same position?
Now you have a huge problem. I would pass! What could you make? Partner is likely to be off at least two aces and two trump tricks (playing in hearts). I'm not going to go looking for a diamond fit. Don't even talk to me about playing in notrump (how can you get to partner's hand ever?). I'd pass and hope the opponents balance so I can double them.
Make sure that you don't get stuck thinking "shortness is good". It's much more complicated than that. The things that make shortness extra valuable are the things we learn from experience in the play: allowing more ruffs in the SHORT hand. Additionally, having shortness opposite partner's length is usually a sign to slow down.