A recall is only issued for safety issues, luckily all Ford's engine problems aren't a safety problem just a pride killer...
They have the option to fix non-safety problems and manufacturers sometimes do this, essentially based on their cost / benefit analysis.
Some actuary at Ford (or GM, whoever) sits down and goes, hrm, this HPFP is failing a lot more than we thought, it's costing us some warranty repairs, and probably losing for life some number of customers we've denied warranty coverage to when maybe it's questionable, and then they have settled some civil suits over this too (if you believe what a few owners say on forums.) So they go, well, the cost in lost reputation / future sales is X, the cost of warranty repairs is Y, the litigation and settlements cost Z, now what is more, X+Y+Z or the cost to replace the HPFP with a different design, upgrade the water separator, or whatever the fix might be?
Also keep in mind they might still be in denial, maybe diamondpilot is right and these stories are exaggerated, and maybe Ford, Bosch, and Motorcraft (?) have not put their heads together and figured out what they would even do if they decided to pro-actively replace parts to prevent more failures.
It is a "Ford engine" with a Bosch fuel system and there is bound to be disagreement about if there even is a design flaw / more failures than can really be accounted for by bad fuel, and if so, which party is at fault and what is the most cost-effective way to fix it, in future model years and maybe on already sold trucks.
Duramax is not really a "GM engine" either, of course. It is a joint effort by GM and Izuzu and Bosch supplies, you guessed it, the fuel delivery parts. So I am not meaning to take anything away from Ford by saying "Ford engine" is not correct; rather make the point that Ford suppliers have a lot of involvement here also.
