Hello. Usually i use Firefox. I was religious about using two extensions, noscript and privacy suit. Recently i've been using Midori, and i like it quite a bit. Midori has the ability to block scripts but because it doesn't have exceptions, it makes some websites i visit like Facebook unusable, so that's a nogo at the moment.
Being religious about them two extensions on Firefox, and having almost no knowledge on securing a computer, i feel a little vunrable without them add-ons.

You guys that actually know what you're doing, do you think these extensions are necessary, and is it fine to not use them?

The more steps you take to limit your exposure the better. I also like to use https everywhere and a good hosts file.

For security I use NoScript, AdBlock Plus, and Redirect Remover.

While all of this is personal preference I am happy with those 3, I might try out Privacy Suite oneday though.