The errata'd Righteous Brand actually can't really be defined as one of the best Leader powers in the game anymore, sadly, particularly as it is worse then Wis-Cleric At-Wills.
Uh, granting a +4 power bonus to attack rolls to an ally is worse than what? lol. Sorry, this is just not true. RB is no longer FLAT OUT BROKEN, but it is still fantastically effective right up to the top of epic tier. Very few leader at-wills are competitive with it in the buffing department.
The problem is that all of the "good" attacks are based off Wisdom or Charisma. But then the damage is +Strength bonus. Or I have a Strength-based attack that grants temporary HP based on my Charisma bonus (+1) which is almost useless compared to the +5 I could get from a bard.
Except this again simply isn't true. I don't know where you get that from. IF you have a high CHA then there are absolutely some wonderful powers to leverage that with, and IF you have a high WIS there are also wonderful powers to leverage THAT with. Having DMed a group with a well-made STR cleric in it all through heroic and into paragon I've witnessed it in action. A STR/WIS strength cleric build kicks butt and has no problem with dumping CHA to a tertiary. In fact it isn't even really worth bothering with CHA in this case, just drop the points into CON, you'll be happy for the hit points.
For a PHB1 cleric to be as good as any PHB3 class, you have to have high scores in Str, Wis, and Cha. On top of that, being forced to have high Wis and Cha is sort of like wasting your ability scores anyway, because they are reduntant bonuses on Will Defense.
See above. Play a STR/WIS cleric and you'll change your mind on this. CHA is not a vital attribute for this build at all.
Unless I'm just not understanding character creation, which is a possibility.
No, I don't think you're failing to understand character creation, I think you are just highly overestimating the requirement for a high CHA with this build.
Spreading around the ability score bonuses means that your PHB1 cleric will probably have a +3 in his highest ability score. An Essentials cleric will probably have a +4 or +5 in his highest ability score. A big difference at the current level (3rd).
The problem with the Essentials cleric is that they are ... a little on the boring side ... and they're not on the working CB.
Retreater
Again, there's no need to spread anything around. You simply have to take the right powers. With a good WIS you can take certain WIS based powers, but you just mainly concentrate on the STR based powers with WIS riders.
Just consider for instance a level 1 STR cleric with an 18 STR/16 WIS, you have Righteous Brand and Lance of Faith as excellent at-will choices. LoF will be 1 less to-hit vs RB, but it targets reflex, so it is actually the more accurate of the 2 powers on average, where's the lack of support for choices there? Healing Strike is a great level 1 encounter power, but all 4 of those in PHB1 are perfectly usable (wow with Cause Fear you might make the enemy move away only speed+1, but it is a crappy power anyway and the difference is minor). Level 1 daily powers? The choices again are basically any of them you want to use in PHB1, CHA isn't even a rider for any of them.
I don't disagree that there are some VERY good powers that rely on CHA to be really effective, but they aren't the only good choices. At high heroic tier PHB1 gets a bit more sparse, but you still have choices and DP certainly provides good additional options. A WIS/CHA cleric surely has more higher level power choices, but not by as much as people seem to think, nor are those choices better.
No, STR cleric is IMHO the strongest cleric build there is when you actually look close. It MAY be slightly eclipsed now by Warpriest, but it absolutely competes with and IMHO blows the doors off the laser cleric.