Why aren't melds a factor in item level?

So the main class I play as is bard. As many bards know, the current BiS includes many pentamelded crafted items. From what I've found this: http://ffxiv.ariyala.com/PEAO is the true bard BiS whereas this: http://ffxiv.ariyala.com/PN9J is the most reasonable BiS (true BiS would cost over 100m gil to make most likely).

Now I can have fully pentamelded, ilvl110 crafted gear, and my gear will be superior to say someone with full ilvl120 gear. Even when I have BiS, I will still have about half or so pentamelded i110 items, yet my overall ilvl will be much less than 130. This makes joining parties with certain ilvl requirements via party finder and potentially duty finder instances more difficult, as I will appear to be a lower ilvl, but my real ilvl is actually much higher than the game thinks it is.

Could SE not implement a way to calculate an item's "true" ilvl based on the melded materia attached to it?

This is an excellent question. I also use some pentameld i110 gear and parsing results are much better than with their i130 IW counterparts so this could make sense.

Im not sure if the system could be able to "detect" which kind of materia did you put on your gear tho.

For example, if you meld 20 VIT and 20 PIE on a bard piece of gear just to increase your ilvl it should not be treated the same way than 20 CRT / DET. This is an extreme case with irrelevant stats of course but... not sure if the ilevel calculation could factor the weight of all stats even if we only consider the relevant ones.

Though any reasonable group in party finder will see that it's logical to allow crafted gear in substitute for higher i level gear, the problem compounds when, if in this instance, final coil hits the duty finder and has an ilevel requirement along with it.
After spending weeks to months clearing turn 9, I couldn't even enter the duty finder version, with echo no less, due to insufficient ilevel.

Of course you can swap gear as a work around, but that seems entirely unnecessary.

There's been several threads about how the ilvl system is bad for various reasons. There also needs to be weights put on slots. Someone with all i100 pieces except a 130 ring and a i70 weapon is not going to be equivalent to someone with i100's, a 70 ring and a 130 weapon. Not even close.

But one of those threads got a response from a rep saying they don't see a problem.

Weapon ilvl should definitely be factored in with average ilvl as a requirement. If something require average ilvl of 90, you should also be required to have a 90 weapon.

I'd love a link to the thread with the SE response if possible. Whatever SE employee said that there wasn't a problem with the current ilvl was terribly incorrect. Glad to see I'm not the only one affected by this, though. I really don't want to have to need roll on ilvl 130 items just so I can carry them around and put them on until I enter the duty finder, then put on my superior crafted gear. Not only is that silly, but I don't need those items and they could be going to someone who does.

Would love an answer from SE on this.