Drop Pods aren't fast vehicles, unless that got FAQ'd.
They're still walking, and Gate can be shut down, not to mention the usual problems with Deep Striking (Mystics, proper deployment, placing 11 big bases anywhere).
3 AV10 artillery pieces that get destroyed by any penetrating or glancing hit? The epitome of survivability compared to those silly tissue box Land Raiders.
Yes, Psykers. Just use transports, or just gun down the T3 dudes, or bring a hood.
4th ed? You mean the edition where missile launchers could destroy them and storm shields and PotMS weren't awesome? Too many points? At 2500?