I know this is really stupid, but...
...What if summoner spells worked a different way? What if they were chosen through the in-game shop, and gave you ONE spell at level 1, and then give you access to your second choice a few levels later (like level 5 or something). I can already think of one or two no-nos that may come with something like that (I can already see everyone choosing flash first anyway, except junglers who are forced into smite), but I mean... something in place that would force people to have to choose based on how they want to play the early game lane. Aggressive ignite? Map-roaming Teleport? Escape/engage flash? Sustain heal?