Strength and bless only give you +1 to your stats? Sounds like you don't have high enough eval int. Bless should give something like +19 to everything when you have 100 magery and 120 eval int.
In this way mages can be both very helpful and VERY dangerous. Also, it seems the damage of damaging spells may also be increased by eval int although they are still mostly not on par with druid spells.
As far as strengthening mages without letting those bonuses apply to magery for druids (not druid’s druid spells but their magery spells), seems a bit unfair since druids are mages too and are in fact required to have magery just to be druid. Yes, druids are powerful, but thing is, you have to have to use up at the very least 300 skill points (and I'd say at least 400 to be able to effectively use pets at all and 480-600 if you want to be a great druid), and you must wield the druid staff and have the druid book of spells (or scrolls) to use any of the spells. So, there's plenty of requirements to be a good druid, they aren’t powerful for no reason lol! (Also, druids are already somewhat restricted because neither eval int nor “spell damage increase” nor any other damage enhancing ability affects druid spells directly so far as I’ve ever known. There are perhaps still tricks to help your spells be more effective, like maybe discording your target or etc, but that does not directly enhance druid spell damage, it just weakens your target. Also, druid spells are not craft-able so far as I know so could not be “made” with any instant cast ability and so are limited in that way already.)
As far as I can tell, PURE mages (using only magery, eval int, inscription, focus, meditation, and healing stuffs) are mostly for support rolls as has been stated: for shooting spells from the back lines behind the safe protection of good tanks and for healing/rezzing others and casting other support spells. They can also be very useful partners in pvp.
Impure mages however are DEADLY in pvp (I’ll leave the discovery of how so up to you hehe) and very versatile and useful in pvm as they can play a variety of rolls depending on their template. I don’t think many really make super PURE mages. Most are probably impure at least to some limited extent even if it’s just by adding hiding and stealth to their template. which gives me ideas LOL! Well, anyway… hehe
Also, a tip as far as spell interruption: use the protection spell

and as far as instant cast, get enough FC and FCR and it should be close enough to instant hehe. Also, with augments to help your FC and FCR and with a max natural rate +3 FCR on jewelry, it shouldn’t be too hard

However, all that being said, I don’t think it’d hurt to improve magery a bit using instant cast scrolls. Also, as you stated, it might make inscription even a little better. Scribes can already make some AMAZING and very useful spell books (I love the mana-regen ones as well as the “spell damage increase” ones and the LMC ones lol). Still though, I’m probably in the minority as far as using spell books heh, so adding instant cast spells might possibly make it a tad more appealing to have inscription (for other than spell damage and casting bonuses and spell book making) and maybe also encourage people to be better (more pure mage skills like eval int and inscription in their template) mages.
-edit-
I *think* you maybe can still use camping to log out safely in the “wilderness” using a bedroll, but I’m not 100% sure. Anyone know? In that way, it might be a bit more useful for more than just stat gain and RP (like if you’re in Fel with no moonstone). But even so, a regen rate might be neat/nice as Wuffy suggested.