Im guessing this is because when the FOV is larger your character is not as physically close to the textures.
Beth optimized the textures for middle distance viewing (eg for consoles players playing on HDTVs and sitting on their couch)
Try it and see if you also have (the appearance of ) sharper and cleaner textures. As far as I can see there is no performance degradation and a larger FOV is quite welcome.
a fov of 75 or 90 works quite well.
What I did. (playing on ultra settings and with antroscopic filtering forced to 16 in nvidia control panel.)
1. added to SkyrimPrefs.ini in mygames folder (not steam folder)
(add the below under the [Display] heading)
fDefaultWorldFOV=XX
fDefault1stPersonFOV=XX.XXXX
eg for fov of 75 change to
fDefaultWorldFOV=75
fDefault1stPersonFOV=75.0000
enjoy



