now moving on to a rational argument-
I make two conjectures:
A- Helping a party you are in to the farthest reasonable extent is expected of everyone who joins a party. it is implicit when people group that the function of the group is do to a quest more efficiently and safely (and also perhaps to socialize, but that is irrelavant). Otherwise there would be no point in the group
B- Making a more effective character is a widespread goal that many many players aspire to within reasonable limits. if you purposely want to use an noneffective build, well, slotting haste is not really an issue of contention, but this is a small fraction of players.
so. Does haste cause an unreasonable sacrifice to a build or playstyle? no. there are precisely 4 good dps spells 3rd level for a given savant (i assume displace is slotted in the 5th spot), and using even 3 in a spell cycle would lower dps. Hasting the party every now and then represents an insignificant amount of sp usage. Haste is a nonexistant sacrifice.
does haste cause an unreasonable sacrifice in terms of grinding? no. haste is easily acquired
is haste a benefit to the party? yes. a 15% increase to melee and/or ranged damage is significant. many fighters would kill for a claw set, which represents less than 15% of almost any melee's dps. a 32% increase in run speed is an added benefit for the whole party.
does haste make for a more effective character? yes. explained above.
in conclusion: assuming characters are like those of the vast majority of ddo players (desiring to help the party/build a more effective character, but not making unreasonable sacrifices), there is no reason not to take haste, but good reasons to take haste. Therefore, sorcs should take haste.
what to do with players who choose not to take haste is a matter of entirely different contentions, as is whether or not telling players that haste is a good idea is right or wrong. these can be moved to a different thread.
Note- there are certain very specific instances where you might want non-dps 3rd level spells (halt undead, waterbreathing) might be wanted. All i can say about these is that sorcs are not made to be able to adjust to very specific quests quickly, and it is debatable if spells like those should be slotted 4 days at a time, considering that halt may be scrolled for the mindless undead in the only truly challenging undead quest, tomb of the wiz king, and waterbreathing is barely ever necessary, i feel safe in disregarding these spells, there are other nifty spells, but they all have better versions.)
(page 37, almost plaid!)