My experience in my last game session suggests this isn't necessary, at least not at heroic levels. (I think Steading of the Hill Giant Chieftain is paragon.)
My PCs have two leaders in the group, and one is a dwarven cleric who is as heavily specced in healing as you can be without being a pacifist or having lots of Charisma. (He even multiclassed with warlord, just to get a 1/day Inspiring Word.) They also have high AC, making it challenging to hit them without magic.
I found two ways around this - high damage (naturally) and redesigning martial NPCs.
In the first case, I looked at Threats to the Nentir Vale and noticed their gnoll warlord. He had a flat-out +1d6 bonus to damage (the warlock curse mechanic, but nerfed and simplified for NPC use), which is about +25% of the damage a regular attack should dish out. In addition, relooking at the DMG II companion rules, it said companions should get sneak attack (even in cases, like rangers, where they shouldn't).
In short, artillery needs to do more damage, much like brutes. So in the first encounter last session, I used crossbowmen who had a nerfed version of Hunter's Quarry, giving them +1d6 damage on their next ranged attack if they used a minor action (which could be stopped by the PC psion's dazing attacks, naturally). Even though I forgot to use Hunter's Quarry a few times, all PCs except the cleric had fallen unconscious at least once, and the cleric literally ran out of healing (he even used up Cure Light Wounds). The encounter was matching the encounter budget, and yet the PCs were losing ground despite using good tactics (the crossbowmen and enemy controller wizard were at -2 to virtually every attack due to the PCs being prone most of the battle), and they only won when a player showed up late, and so his PC was at full health and all of a sudden the encounter budget was off
The PCs were at a disadvantage in part because they were used to winning all their encounters, which they'd done easily for about three sessions in a row.)
If you don't give the monsters enough hit points, they don't last long enough to do anything interesting. PCs do quite high damage with action points, dailies and striker powers as it is The battles might not seem exciting if they're not taking enough damage, but literally doubling damage is too much. +25% damage on
some NPCs was enough to make my highly optimized PCs fall like flies.
The second issue was high AC, which might not apply to your PCs, but if you've got someone spending four feats on boosting AC, it might be important. I would just give various giants attacks that target Fort and Reflex, frankly changing whatever the stats say in the adventures or monsters books. (I inflict the -2 penalty to hit on these attacks since they're not against AC.) Don't be afraid to up the challenge if the giants aren't dangerous enough, such as turning recharge when bloodied powers into recharge 5-6 powers, or giving giant artillery various bonus on thrown rock attacks, or the like.
I do agree on using inherent bonuses, but this might actually backfire in this adventure, as it's not written assuming that standard. You'll need to nerf treasure somewhat.
