Warrior is a low cohumulone, high alpha, moderate myrcene %, low total oil content American hop. Translation: It's great for smooth bittering, but not so much flavor/aroma. It's composed of faint citrus and grass. Maybe a tad more aromatic than Magnum, but still very mild. Every hop has a purpose... and in my opinion/experience, Warrior should be used for bittering, not aroma. Hops like Amarillo, Citra, Simcoe, Centennial, Columbus, etc. are much more aromatic by far.
FWH is not necessary, but it's not wrong either. Your choice to FWH with 1.5 oz. Warrior or to simply bitter with 0.75 oz. Warrior. But any gains you see in "smoother bitterness" from the FWH is inconsequential when compared to a traditional bitter, especially for an AIPA, because: 1) you are using less of it at half the amount, 2) Warrior is already an excellent low cohumulone smooth bittering hop, and 3) hopbursting and dryhop additions with more aromatic American hops will help to round out much of the early kettle addition bitterness to create a sense of hop juicy-ness and smoothness.
So with a traditional bitter, you can still have smooth hop bitterness with very high aroma and flavor. If you're a fanboy of FWH, but want to use less early kettle additions and still achieve the same level of smooth bitterness, then you just have to get into the habit of using 95% of your hops late and significantly cutting down on the amount of your typical high-alpha bittering addition at 60. I've also found that supplementing a small amount at 30, or midway through the boil, can also help to round out the bitterness. That is another technique you might want to look into if you wish which will still allow you to use less hops early on.
