Variety is the spice of life; with the addition of Holy DPS

The benefits brought to this game with the addition of Holy having a second viable role in the talent tree would be tremendous.

With the addition of Holy DPS, spell power plate gear will finally benefit more than one spec. Spirit is already converted to hit for Holy Paladins with a talent, and mastery will be dealt with in a bit.

Variety is the spice of life; with the addition of Holy DPS, that would open up another playable spec to the game. You can throw homogenization as much as you like, but a new, different spec, is a new different spec. With Holy Shock, Holy DPS paladins can juggle using Exorcism or building up Holy Power for inquisition.

Finally, it would be implementable. I'll refrain from saying easily, because I'm not the one who will be crunching numbers for it. However, Blizzard shows they can do it. The Feral spec for Druids holds both a tanknig spec and a DPS spec in it. It has split masteries and role specialization bonuses, and I'd suspect Blizzard cold do the same for Paladins.

With a few talents modifying key spells, like increasing crit damage of Exorcism and increasing the damage benefit of Inquisition, paired p with Glyphs that could increase teh cast time of Exorcism with the benefit of an increased coefficient, and perhaps a glyph improving the damage of Holy Wrath.