Me, for one. But then, I don't use anyone's messaging software, ad supported or not.
"Ad is just an exchange for free service."
That's like saying, "Money is just an exchange for free service." After all, money is just paper and coins people agree represent a defined value in a monetary exchange. Ads cost me time, screen space, and bandwidth, and I pay money for two of those three.
"Not all freeware are 100% free. It usually has feature limitation and force you to buy shareware for full feature support."
All freeware IS free; you're describing 'trialware' with a limited feature set, not 'freeware'. There's nothing wrong with adware, trialware, shareware, etc.; there's something wrong with them falsely advertising themselves as 'freeware' when they're not.
You're new here with an uncompleted personal profile. You don't by chance develop on-line applications for distribution in exchange for advertising revenue, do you?