Using the Orog for my Pathfinder campaign, which is pretty equivalent to 3.5 for power balance, I think +3 ECL for Orog characters seems excessive. If a base 3 HD Orog is CR 2, then +2 ECL seems like plenty of penalty for character levels (as class level = CR for NPCs, so I feel CR should generally be an accurate gauge for ECL in templates).

My preferred version: As an alternative to that system, however, I would suggest that Orog characters (NPCs in most games) should ditch the humanoid hit dice and replace them with all character class levels - just like a human Fighter does not start with Warrior levels before switching to Fighter. I think talented orogs who can achieve character class levels would usually start training in those roles from a young age, where their talents would quickly shine through in the harsh "survival of the fittest" world young orogs must survive. A human child who grows up to be a fighter might still be counted as a 1st level warrior if thrown into combat while still a trainee at age 12 - but they wouldn't be stuck with this warrior level the rest of their lives! Why not treat other sentient humanoids the same way?

As a I DM might also reason that the extreme brutality and survivalism of orog culture might generate not only many more warriors, but also push the most creation of most gifted competitors - thus breeding more character class NPC elites and leader-contenders in the society. By the time an orog competitor is deemed worthy of initiation into the ranks as an adult Warrior of the Tribe, they are typically either a 3rd level warrior (or expert?) or a 2nd level NPC. But PCs might easily meet or fight 1st and 2nd level orog trainees mixed with veterans on live missions (similar to the squires and pages of knight units, but with an "everyone fights" hard rule for orog units).

How about an Orog Character Template with no level adjustment?
Then every orog could have class levels - either Warrior by default, or class levels for NPCs.

Orogs may have some powerful racial advantages in physicality, but they also have severe disadvantages - most of them social and political. A race taught by the religious decree of their one true god Torazan that all other races are inferior and their sworn enemies, don't tend to play well with other species (and things are probably pretty tense to outright violent between orogs a lot of the time, too, especially outside of their established groups: units, bands, gangs, temple, families?).

Being exclusively nocturnal / underground severely limits their options on the surface world, especially in the summer half of the year when the sun-lovers are most active. As a PC or NPC, this really limits action on the surface world - where most of the life, wealth, and opportunities in Cerilia exist.

Canon lore says orogs are never seen on the surface while the sun is in the sky. I would suggest this might create a stronger aversion to bright light - or perhaps only to true sunlight - than merely being dazzled (-1 attacks) in bright light. Such a minor annoyance would be unlikely to make armies or bands of orogs keep from operating by as much as 18 hours of a day in the northern latitudes in summer, especially when there is a war going on!

I would make light more dangerous and possibly paralyzing for orogs - making light sensitivity a stronger disadvantage for them. Detailed below for Pathfinder, which uses the sickened condition: -2 attacks/damage/saves/skills/ability checks. Conversely, I'd also give them the darkvision of a truly subterranean species: 120'. It would be a powerful advantage over their rivals the dwarves, and give another reason why the orogs have been slowly winning the wars for the underworld over the past few millenia.

Orog Template (Pathfinder 1e)
Medium Humanoid
+4 Strength, +2 Constitution, -2 Charisma
speed 30'
Special Qualities: darkvision 120'
light sensitivity: Orogs are dazzled in bright light and indirect (overcast) sunlight.
Orogs operating in darkness who are struck by or first enter a bright daylight spell or similar effect must make a DC 15 Reflex save to avoid being dazed and blind for 1 round.
sun sickness: Orogs caught in direct sunlight also suffer agonizing burning in their eyes and on unprotected skin. When first struck by direct sunlight, and every hour thereafter, an orog must succeed at a DC 17 Fortitude save or suffer 1 point of damage and become nauseous for 1d4 rounds, and sickened thereafter (-2 attack/damage/saves/skills/ability checks). A successful save still leaves an orog sickened and dazzled in sunlight.
Light-based and sunlight spells include the equivalent effects listed above, and deal enhanced damage to orogs as if they were light-sensitive creatures.

Background Class Skills: Perception (spot/listen), Warcraft
Racial Bonus Feat: Toughness