First of all, what more do we need, if the majority of the players of the product want it this way?
Second, let's remember that the concept of the holy warrior has always been around in fantasy, even from the tales of Lancelot and before.
There is an archetype, and that very archetype is as early as the Maiden Jehanne: Joan of Arc. This is the archetype of the "called warrior," the warrior that has been called by their deity to go forth and accomplish a specific mission. These are not necessarily spellcasters, but they are usually considered tougher than ordinary beings, and exceptionally lucky in some way. Depending on who you ask, this type extends through Chronicles of Narnia in the form of Aslan, and even into the Lord of the Rings.
However, these people were not just called later in life; they were often called in their youth, at a time roughly equating to first level. Taing this option away invalidates a very good roleplaying experience, that of the called warrior.
DO I believe they should open the class? Probably so. In a pantheistic society, there is more than just Lawful Good to aspire to. Each god should indeed have a holy warrior option for their champions. The Forgotten Realms design team solved this with the Champion five level prestige class, but it is still not the optimal solution, in my opinion.