To use another example: the SR-ignoring makes it fairly easy for a 5th-level orb conjurer to kill a CR 13 iron golem. This problem goes back to the change to Acid Arrow in 3.5 (which will also let a caster kill a much-higher-CR golem) and the change to golem's magic immunity. Not sure if the interaction of these two changes was considered thoroughly. The orb spells exacerbate the problem by introducing new damage types (force and sonic being the worst offenders) to the no-SR energy-damage club. Demons and devils can shrug off Acid Arrow but not Lesser Orb of Sound.
The SR-ignoring makes the orb spells killer against monsters whose main defense is SR. Dragons are a poor example, as their SR is typically CR +6 to CR +8, so not all that potent. Mind flayer's SR is CR +17, Rakshasa is CR +17, and most devils are CR +12. These monsters should be highly resistant to direct spell attacks from PCs.