Why Did God Use Plagues?

Considering God's omnipotence, I find it odd that God would use plagues at all. If He just wanted the Israelites free, couldn't He have accomplished that more directly? Instead of subjecting everyone to one plague after another, God could have just killed the Egyptians or had the Israelites jump straight to the part where He splits the Red Sea. Perhaps God spent all that time on those plagues largely just to prove that He could. Maybe He wanted to make sure that both the Egyptians and the Israelites know how much power He had, and perhaps He wanted to teach that lesson over the course of enough time to make sure that the message actually sunk in, or at least should have sunk in. After what must have been weeks, if not months,of supernatural events, both the Egyptians and the Israelites had had plenty of time to learn that God was a supremely powerful being, and one who should not be crossed. Yet, the two peoples went on underestimating Him, and they ultimately got what was coming to them, but after all those plagues, you couldn't say that they hadn't been warned.

Sometimes, God does something different from what we thought He should have done, and that is never for lack of ability. God can do literally anything He wants to do, so when He used plagues to eventually free the Israelites, that's not because He couldn't have done it any other way. God could have free the Israelites more quickly and less destructively, if He had wanted to, but for whatever reason, He decided that a series of plagues were the best tool for the job.

We don't always understand why God does what He does or why He doesn't do something else instead, but we can know that it's not because of any lack of ability. God can do whatever He wants any way He wants, but He always does what's best, and He does it in the best possible way. We might be able to think of a number of "better ways" to free the Israelites, but God knew the best way to secure their freedom, and that way, for some reasons,  involved a series of plagues.