I left it at the base value of 8. I don't want more than 2 followers. I plan on a generic explorer character. No power gaming, uses melee and a couple of magic buffs. Thanks

You need Charisma if you want to be persuasive and/or want a lot of followers, so you should be fine.

When evaluing your charisma in arcanum theres 3 factors to consider:
#1. your beauty, IF U HAVE TO LOW beauty and TO LOW charisma, you're basicly screwed, make sure at least 1 is above 6 so that you're not randomly attacked, id advice to at least have both above 5 and 1 above 7 so you can pick up most quests

#2. Followers, you seem to have realised this 1 allready, but especially when creating a mage char you should realise the charisma req for picking up [spoiler] sogg mead mug [/spoiler] etc, also its naturally effects max followers (but actually having less followers tend to give you more #of hits and again makes it easier to level in the game so :)

#3. Persuasion, bonus quests, bonus rewards etc: this is kinda the real roleplay part of the game, this will not make the game genericly easier, from my experience it makes it harder, but it will in a lot of areas make it more fun, the coolest thing with charisma is when you convice [spoiler] Loghaire [/spoiler] or others with you, it also often allows for unique solutions, that might give worse rewards(in form of less loot) or less xp, but more "desireable" solutions tho.

Especially as a magical melle fighter charisma tends to matter very little, if you try to play a automatician+gunmaker/gunner+Electrician type char, you suddenly will want at least 2 followers (unless you pick up [spoiler] dog [/spoiler]but that char is so strong i don't do it because it feels like cheating :)