I wouldn't totally rule it out. I think both parks are great for all ages. My cousins have enjoyed both when they were toddlers and there was lots to do. We will be going with my toddler (who will be days shy of 2) and 7 year old at the end of August and will probably be spending 2 days at BB and 2 at TL so I will update then and let you know which he seems to prefer more.
Blizzard Beach has Tike's Peak. It's separated from the rest of the park and only has two entrances, which makes it easier to contain toddlers. There is a sandy area there for building sand castles and plenty of seating (some of which is covered). There are three really small slides that toddlers can easily do alone as well as three slides that are a little bigger (but still made for small kids), one of which kids go down on a baby tube (no hole in the middle). There's also a wading pool/ splash pad area that's only a few inches deep with spraying fountains.
Typhoon Lagoon's Ketchakiddee Creek also only has two entry points. There's a splash pad area with small caves and tunnels, waterfalls, and a tug boat that kids can climb in and shoot water cannons. There's also a sandy area there. There are a few small slides including an inner tube one for small kids. Toddlers could also go down the Bay slides (for kids under 60") that let out into the shallow end of the wave pool, though I would recommend one adult at the top sending the child down and an adult at the bottom to catch them.
Both water parks also have the lazy rivers, wave pools, and family raft rides which toddlers may like. You can also rent life jackets for free if you want your toddler to have one.
I think the water parks are great and wouldn't go to Disney without going to them. Obviously, everyone has different opinions and hotel splash pads are great, but not the same in my opinion. As stated before, I will give an update at the end of August/beginning of September (though it might be a new thread) on how my toddler fares at the water parks.
