Currently, Wizards are awful in Epic/Legendary. Because of the amount of hitpoints and DR the mobs have in EE/ER/LE/LR content, Wizards are almost impossible to play and do well, unless you are a competitionist maybe. A first lifer doesn't stand a chance to solo anything EE/ER/LE/LR even if they buy and use a 1000 superior spell point potions. The Wizard enhancement trees need to be updated and brought in line with the current Epic and Legendary content; I believe the wizard enhancement trees were created around the time of the Underdark expansion which would put it back into heroics content and date it about 8 years old - which is fine for heroic content, but for EPIC/Legendary wizards sit at currently the worst of all the casters and not by a little; they are spell point starved, damage neutered, enhancement gimped - having only heroic viable SLAs - into epic and legendary the Pale Master tree, Archmage tree, and Eldritch Knight tree fail completely all being out of date compared with other classes in the current content. Make your wizard a drow and you literally may be on the weakest playable toon currently in existence in DDO.
Are there any plans in development to update the Wizard?
Eldritch Knight tree needs to be completely re-tooled. Currently it is a mess; yes it allows us to wear medium armor and grab PRR which is great, but it requires many points to be invested with not much benefit. Compared to the new Druid or Favored Soul, or even the Warlock Enlightened Spirit tree, the Eldritch Knight tree is a joke; it needs to give way more PRR/MRR, like wayyyy more. It should be either re-tooled or replaced with a new enhancement tree altogether.
Archmage is probably the most outdated in that the SLAs come too late, cost too much, and are all evaded by EPIC/Legendary mobs reflex saves and their damage is suck ass poor. There are way too many old metamagic optimizing buys and too few useful things in the tree - again compared to the new Druid trees, say, the Archmage tree is mostly useless - you can grab spell pen and spell DCs which are nice, but in EE/LE/ER/LR content over 40% of mobs are deathblocked - why is that? It makes a DC caster completely useless, or forces them in to Shiradi - which is fine but most DC casters are in Magister not Shiradi. It isn't a fun endgame for a wizard to be unable to do anything in endgame content. The Archmage core enhancements need more things in line with the new DDO legendary content, to make them viable casters.
Pale Master is great in heroics but once you hit Epics and legendary become a complete disaster. The skeleton pet becomes useless and costs way too many points - it should cost a total of 6 AP to get a lvl 30 skeleton not 18 points to get a heroic capped idiot skeleton who does literally nothing but chain die. The SLAS need to allow all metamagics be applied to them to allow them to scale correctly to level 30, they do negligible damage in Legendary content now. The entire pale master tree should be rethought to add more necro spell SLAs and work like new druid tree or favored soul tree. Stances like 'vampire' 'wraith' and 'lich' should be made into separate enhancement trees similar to 'Falconry' or 'Vistani Knife fighter' or 'Harper trees.' That way any class could splash into an undead tree - since being undead should not require one to be a wizard. Undead monks, warlocks, druids, etc would be very fun. While you're at making 'Lich' and enhancement tree like 'Harper' consider too a 'werewolf' enhancement tree. Would be very fun too and inline with the core rules about lycanthropy.
Currently the Deep Gnome iconic makes the wizard slightly more viable as an illusionist, but in EE/LE/ER/LR content as I said before 40%+ things are deathblocked or immune to PK so then what? The illusionist has 2 spells - PK and Hypnotic Pattern - there needs to be many many many more spells added to DDO including illusionist spells; the core rules has many. I think its time to add more spells to DDO.
I hope to hear that Wizards are getting a pass soon - especially the pale master because I know many people who play this and spend lots of money to make their undead wizard viable. They shouldn't have to - its agonizing to be on such a core dungeons and dragons class - wizard - that is so impractical for Epic and legendary content.