Actually the hive mind has displayed superb intelligence many many many times over. Who needs careful strategies when you can just zerg rush an enemy. Remember, the tyranids digest bodies, friend or foe, dead or alive. So they have no reason to worry about casualties. The only cases in which they have ever used tactics and strategems is when the zerg rush fails, and when they do use tactics they tend to be spectacular. Entire worlds have been known to be destroyed by single tyranids alone acting intelligently. It is also known that the higher the synapse present the more intelligence that an individual tyranid will display. Lets face it, as far as tactics go in star trek... there are practically none at all, what few tactics exist are rudimentary and basic at best. And we both know that even if the UFP could kill 1,000 nids for every man they lose at the end of the day the nids would still win.