It can be waterproof sealed without the glue. I used my Kyocera Torque (rugged) until I couldn't update it's OS. (needed updated software for work) Changed it's battery once, you could use a nickel (or a fingernail) to unlock its backside and pry it open with your fingers. Battery slipped right off. Waterproof and tougher than a Nokia. I still use it as a hammer.

I am not sure the glue is that necessary for a waterproof seal, hence the crap.