if most reviewers say they can notice a difference in sharpness can you post couple of review that say that??
Sure thing. To be fair, I will pick some from the front page google search for "Moto X review"
androidauthority
"While 1080p displays are quickly becoming the norm, and even though I cringe at anything less, this is a very nice display nonetheless."
Marques Brownlee See Moto X review Time: 4:00 minutes~
Time 4:00
"The only time I can see a difference of this and a 1080p display is when you put them side by side."
AnandTech:
"I can detect a difference between the Moto X and the really high DPI displays like the HTC One and SGS4, but it isn?t something that bothers me when using the Moto X."
The Verge (also makes comment about the S4's screen)
"though not a best-in-class performer like the HTC One?s Super LCD display"
Cnet
"The screen isn't as big and sharp as those on some competing handsets."
Many others including Android Central implied that the 1080p screen would or does look better however the 720P screen is sufficient.
I am not sure why people are crying about pixels density saying that if a ppi is 300 or higher the eye cannot discern the pixels. Who exactly cares about the pixels themselves? Even though we can't see the pixels, we CAN see large cluster of pixels working together to portray detail in a photograph, a corner in a shape, or a sharp line in a font. The more pixels, the clearer the details.
There is a limit obviously, however 720P/1080p on a 4.5" to 5.0" is discernible.