As most know, very few enemies have fortification in DDO. The only ones I can think of off the top of my head are WF and some epic bosses. Now this mainly applies to rogues since they need to bypass fortification in order to get the majority of their damage (though they will still be doing decent dps if they are a strength build), so I also propose that a new enhancement line should be opened up for rogues that allows them to bypass fortification.
The Opportunist feat bypasses 10% fort while the Precision feat bypasses 25% fort. Naturally, most if not all rogues should have taken the Opportunist feat (unless they are multi-classed and their build demands likewise). As for the Precision feat, it's just plain horrible. I tried it out once, and it even halves your sneak attack damage which doesn't really even make since because you would think being more "precise" would actually improve your ability to sneak attack.
I suggest this to bring a bit more balance and sense to the game. Why would level 20's be running around with 100% while CR 36's have 0% fort? Of course, if the enemy decides to start using fortification, the rogue would be smart to train a bit to slip past the enemy's defenses.
"But Quarterling!" you may say, "this is essentially a nerf to rogues!"
This may be so, but also keep in mind that all the other classes' critical hits have a chance of failing as well, more so since they might not have the option to boost fort bypass. However, I see this as a minimal problem for all the other classes because of how it is impossible to auto-crit come update nine. Many people will no longer start to rely on weapons such as the heavy picks, but instead try to boost their raw dps.
Let's face it, there should have been mobs with fortification a long time ago, yet Turbine for some reason has not implemented this.
Finally, as for an example of the new enhancement line, it could go something like this; and this is based off of how most new enhancement lines will be when update nine comes out, with the biggest bonus at the top and all tiers of an equal AP cost.
Pierce Fortification I (level 3) [bypass 25% fortification] 1 AP
Pierce Fortification II (level 6) [bypass 30% fortification] 1 AP
Pierce Fortification III (level 9) [bypass 35% fortification] 1 AP
Pierce Fortification IV (level 12) [bypass 40% fortification] 1 AP
Pierce Fortification V (level 15) [bypass 45% fortification] 1 AP
Pierce Fortification VI (level 18) [bypass 50% fortification] 1 AP