just gone axe & lovin it !

I can understand how you're thinking, but first, you need to understand how truly powerful Flail and "Save Yourselves!" are.

First, Flail - a 33% increase attack speed which charges swiftly, for a puny 4 adrenaline, yet slows movement rate. Honestly, for PvE - the drawback is negligible. when foes have settled, they generally stop moving and they don't kite often, or well - they suck at movement in general so moving slower isn't gonna affect you much for general PvE. Essentially, Flail has no downside.

Now, for the good stuff. An attack speed enhancer ('IAS' - increased attack speed) - is really, really, really strong. In fact, I'd say that it's hard to find a skill that can increase a warrior's overall damage output more than Flail/Frenzy. An IAS decreases the time between attacks by 33% - there's some silly maths, bunch of numbers and shit, but basically, it adds up to this - while under the effects of an IAS, you attack 50% more. You deal 50% more damage in a given timeframe, and gain 50% more adrenaline overall.
And 50% is huge; there's not one skill that can add that much damage - take an IAS, for PvE Flail is godmode.

Now for "Save Yourselves!". It lasts a puny amount of time, aye. But the actual effect of it is insane.
While up, it gives all party members (importantly, not yourself - more on this in a second) a whole 100 extra armour. Under GuildWars maths, that means they take... ~85% less damage. A Deep Freeze from a nasty Ele boss that'd wipe your backline with 300 damage? Under "SY!", that huge nuke gets turned into a patlry 45 damage. Essentially, "SY!" makes your party nigh-on invincible for a few seconds - a very strong ability, one of the most powerful skills a warrior can bring to the table in PvE. Even at only 3 seconds, it's more than worth a skill slot.

Now, I also highlighted that it doesn't affect you - theoretically, you can abuse the AI here - enemies often target people with the lowest armour; if enemies re-aggro while under "SY!", chances are the squishiest guy is gonna be you, so enemies will fall onto you (certainly, I've noticed my health drop faster when my party is affected by "SY!" rather when they're not). This is an incredibly good thing. The warrior naturally has the armour to take very big hits - no further defensive buffs required - and also, it makes it easier on the team's monks, having one guy taking a beating (and the rest of the partry nigh-on invincible).

The downside of "SY!" is that huge adrenaline cost. However, in reality, 8 adrenaline will come up fairly quickly - wailing on something for 7-8 seconds under an IAS will charge 8 strikes, and you'll charge it even faster with multi-hit attacks like Triple Chop and Cyclone Axe, or adrenaline buffs like "For Great Justice!"

Of course it's up to you, but the simple fact is - Flail and "Save Yourselves!" are very strong, and are well worth stapling to your PvE bar because few skills can do as much for you.