This is quite true. I've noticed more and more penalties being shot right down the middle. In order for a goalie to get to the side to save something out there, they have to go early enough, so if you've got the power it's often better to hit right down the middle.
For those that are science nerds, there is actual research on this and it's overwhelmingly true that goalies stay middle less often that would be optimal. There are quite a few papers on the topic. Here's a relevant table (from CHIAPPORI, P.-A., LEVITT S., AND GROSECLOSE, T. (2002). Testing Mixed-Strategy Equilibria When Players Are Heterogeneous: The Case of Penalty Kicks in Soccer, The American Economic Review, 92, 1138-1151). Basically what it shows is that out of 459 penalties, the kicker went middle 79 times, while the goalie stayed middle only 11 times. The prevailing theory is that there is some additional "psychological cost" to staying middle and having the kick go left or right (basically you look like a schmuck that didn't try to save the penalty) as opposed to diving left/right and having the kick go middle (where "at least you tried"). Hopefully the new focus on science and statistics at Anfield will include these kinds of things!
TABLE 3—OBSERVED MATRIX OF SHOTS TAKEN
Left Middle Right Total
Left 117 48 95 260
Goalie Middle 4 3 4 11
Right 85 28 75 188
Total 206 79 174 459
Notes: The sample includes all French First-league penalty
kicks from 1997–1999 and all Italian First-league kicks
(1997–2000). For shots involving left-footed kickers, the
directions have been reversed so that shooting left corresponds
to the “natural” side for all kickers.