Ummm . . . that doesn't have any effect on rimfires, since the priming is around the outside, ie - the rim.
Not true at all. Check out the differences in BC of triple-shok X-bullets with and without the polymer tip. With the tip, the BC goes up noticeably. That being said, there is going to be very VERY little difference within the max 100 yards (more likely 60) that most .22 lr is used in. Also, the base of the bullet doesn't have much effect until ranges become rather long-ish, like past 500. 2 main reasons that you won't see bullets like that on the venerable old .22 lr is: 1) the case uses a heeled bullet, rather than a bullet that fits entirely within the case as in all the others. Trying to make double-diameter, heeled, boat-tailed, polymer-tipped spitzer bullet in any sort of reasonable cost is basically impossible, which leads to 2) it is far too expensive, and .22 lr has reasonable cost as its largest check in the 'pro' column. Your basic top-shelf .22 lr target ammo that people use for competition costs about the same as a standard box of .17 hmr which people use to hunt with. The low cost is its niche market, and it leaves the high-performance mostly to the .22 WMR's, .17 HMR's, and possibly even the .17 M2's.