Minds eye is less useful now that claw-softening is possible and some weapons have purple sharpness (purple never bounces [edit: I think?]).
Still, it's very nice for anyone still on the story, since you may be using blue-sharp weapons that bounce like hell.
It's also useful for a few hunts where monsters have hard parts and claw softening is dangerous (especially in single player, where you don't have a 4-way cuthc-claw rodeo to keep everything softened)
Monsters like scarred garuga and silverlos have very hard parts and a failed clutch claw attack on the tail/head is going to hurt you.
To be honest, it's one of those "Fuck this bullshit, I should've brought X to this fight" gems for me (
c.f. steadfast and tremor resist). I almost never use it, but often wish I had.
So should I be blasting through the story as a new player? Been trying to play as fast as I can! Been using all the good gear they give you like the defense armor.
I've been figuring that I should keep all my loot and whatnot until I get to the point they want me at.
Go as fast as you like, but you shouldn't stop to 'grind' anything unless you really enjoy the fight.
Keep all the loot at the end of fights. If you need cash for something, you can sell stuff that you have an excess of while back at camp.
There are some low and high rank materials that you'll need as part of the upgrade path for master-rank weapons.
The easiest way to get cash is to use your daily ticket on an investigation that already has a bonus cash reward - and do it in single player. The cash rewards in master rank are high and mean that selling low/high rank stuff for a few pennies is rarely worth it (I mean, you get 3K or 10K zenny just from the pig between every quest in master rank, some investigations give >100K even without a ticket, and the steamworks can get you a lot of cash for doing basically nothing). I think I've seen investigation rewards go as high as 180K, though that's for something insane like a triple tempered rajang/deviljho/rathalos with 1 faint.