Since you guys are comparing this game with RO, let me explain why no cooldown worked in RO and compare it to the ToS system.
RO had no cooldowns (no 3rd classes counted), but it only worked because of three things:
1 - Skills had Delay, so you can’t spam them infinitely with macros.
2 - SP potions recovered SP instantly and were spamable, provided that you wished to invest enough in recovery items, you could cast skills as much as you wanted. Some classes also had skills to increase/give SP to others.
3 - The game had a system that reduced cast time with DEX. While some classes had skills that had no cast time, most major AoE or wizard type skills had long casting times that prevented them to be spammed, you could reduce your cast time but only achieve instant cast in high-end content and using a lot of buffs and with the help of gear and other classes.
For this to work on ToS they would need to do a lot of adjustments in their gameplay. RO was a game where players were used to invest tons of money and resources to get effects (HP/SP recover and buffs consumables) and gear to increase their character’s efficiency. Players would spent fortunes of money before they went to WoE.
But ToS is different from this reality, the gameplay and character progression is smoother (or should we say “lighter”) The game is trying to avoid the “grinding” side of MMOs and instead focus on the exploration/achievement side, they don’t want you to stay hours and hours farming and preparing your wallet to get supplies to enjoy the game, they even implemented main story quests to help you progress through the game.
I agree that they could balance the game to have no cooldowns whatsoever. But they have already decided this on the early stages of the development. Changing this would require to change everything else and it would make a completely different game.
In this CBT I played (Wizard->Pyromancer->Psychokino) and although sometimes I found myself waiting for cooldowns before I killed mobs. MOST of the time I was doing anything I could to recover my SP, using pots as soon as I could and even building a campfire and sitting while my team mates killed mobs. The cooldown system helped me save some SP and it wasn’t even enough. I could solo almost any questline boss, but in the process I had to spent something from 10~15 SP pots to use enough skills to do enough damage to kill it.
But if you remember, early levels of RO was exactly the same. If you played wizard, you would always go looking around for immovable mobs, most of them were plants, and spam your most strong elemental skill on them. Whenever your SP was out there was nothing you could do but sit. In RO you would have no money if you were a starter to buy SP recovery items. At least in ToS they have features to assist you in that, potions are cheap and you have enough money to buy them. The bonfire is also an extremely helpful way the recover SP when you need to sit.
TL;DR: While ToS could remove cooldowns to make it similar to RO, they would have to change a lot of things that already exists to do it. But at the same time, ToS system is really forgiving and in my personal opinion is much better and less grindy than what RO was.