I think both Severance and Kenryoku_Maxis are wrong.
Severance seems to be misunderstanding KM. KM isn't saying that Final Fantasy games are bad due to weak gameplay, he's just saying that the creators aren't focusing on the gameplay. Basically Severance is thinking "He's saying A which means B to me but I don't like B so boo him" when KM isn't saying B at all.
That said, I think KM is overstating his point. Specifically, I don't like this quote:
"there's just the undeniable fact that the vast majority of Final Fantasy games do not require much in the way of planning and tactics"
Most every Final-Fantasy game I've played has required a bit of planning. In Final-Fantasy 1, I planned my team (F/BM/RM/WM), planned the spells they would each take, and chose when to use them in battle. A lot of fights simply would not have been won without having the right spells and using them wisely. In Final Fantasy 7, there is a great deal of planning that can go into materia selection which, prior to getting Knights of the Rournd which you only get at the end from an obscure quest, largely impacts the challenge. In Final Fantasy 8, there's a huge amount of planning in choosing Guardian Force abilities and who to junction them to as well as what magic to add to what.
As for tactics being lacking, I would partially agree with that. You generally know how you're going to fight a battle when you go into it. You're going to use that materia, summon that GF, use that limit break, etc. There are very few instances where you will have to radically shift strategies mid-battle (in fact none I can recall atm).
Now, what is common in a lot of Final Fantasy games is grinding. Grinding can eliminate the need for planning. Outside of certain enemies in the various games, there is very little you cannot overcome by being 25 levels higher than the game expects and mashing the attack command. That said, I don't think the ability to grind to infinity and beyond should be held against it. It's almost like using a strategy guide on a game and then complaining about the difficulty in that you're giving yourself an advantage by doing certain optional things the developer allows.
@the person who said you cannot grind in Fire Emblem: Certain FE games have something called an Arena which lets you fight unlimited battles as long as you have the time/resources to continue.