In theory this is supposed to awaken you because you are a much lighter sleeper during REM, wich in turn should make it easier to feel that you need to go to the bathroom.
I have actually tried this myself several times (usually one or two glasses of water a few minutes before bedtime) and it does seem like this makes me wake up 5-6 hours later with great dream recall - but can this just be a coincidence?
The goal here, of course, is to make it easier to recall dreams and practice WBTB etc.
You might actually be on to something, I wouldn’t try it though since my bladder has quite a large capacity.
Actually, believe it or not this is actually a technique that some people use… I’m so not even going to bother with its name 
Three possible problems. One; you wake yourself up too much getting out of bed and have a hard time going back to sleep, making some techs harder (not a problem if you fall asleep quickly or if your intention is to do a full WBTB where you fully wake up for any length of time). Two; you become lucid thanks to that feeling but the dream is uncomfortable and unstable due to needing to go. Three; you need to change sheets in the morning because… reasons.
Well I wouldn’t rely on that technique too much, although if it works for you then why not.
But for all the reasons Rhewin said and if you think about it why to stress your body like that. I know it’s nothing special but still. You have autosuggestion which can be very good tech and if you combine autosuggestion with Darxide’s EFT techniqueyou’ll get great results!
I’ve tried this technique alone for a week and I get LD’s so combining it with others there is a good chance for some results…
In that case I would need to drink like one gallon of water and sleep so deeply that not even the urgent need to go to the bathroom could wake me up. 
But yeah, I understand your points - it probably isn’t a very ideal “technique”, since it might be kind of stressful for your body.
I was actually getting kind of tired of the technique anyway, since it feels a little uncomfortable to go to bed right after drinking a lot of water.
Lately I’ve been drinking a lot of water to avoid dehydration. I wake up in the middle of the night a lot more often, which is rare for me.
I like the feeling of waking up, only to have a few more hours of relaxing sleep, so I like it when this happens. I was able to focus on a time to wake myself up at and it worked. 
Just don’t drink too much water because the consequences would not be good. xD