Many Caster Heroes have Spells with a very close range. Examples are Zilean, Annie, Ryze. So, to cast their spells they have to go toe-to-toe with their enemy, which they are definitely not good at.The complete opposite of this is the cardmaster. His spell has a large range (one of the reasons he's being considered imba).

My suggestion would be to just increase the range of those short range spells.

Actually I would say decrease the long range spells instead. It would help Melee DPS which are finding it hard to be effective.

Skillshots tend to have longer ranges, which is probably ok, because at extended ranges it's easier to dodge them. The exact amount by which they're longer-range could stand some tweaking. It also gives a serious laning advantage.

As long as those long range spells dont include Cryo's Flash Frost, I'm all for it.

It's funny, Chronokeeper's Bombs are very close range, but he has huge attack range.

Card Master's cards have huge range, but his attack range is garbage...

Wild Cards should match his attack range -- but they should both be about somewhere in the middle of where they are now. One of the biggest drawbacks to a DPS CardMaster is his lack of range.

Well, my intention was to make those casters fit their role: Providing firepower and support from the back. Currently, the distance between them and their target is too close to call it "from the back" imo.

If this would be impleted, there should be also major buffs to other heroes, yes. Sounds some serious work to me and a lot of tweaking.