Have Apple not heard of Time Management?

Not so much a question, more a whinge!

I have just taken the leap from Snow Leopard to Mavericks (one small step for many, one giant leap for me!) and I find the separation of Calendar and To Do/Reminders items into separate applications/apps both a nuisance and bizarre!

I now have to have two applications open to do what one did perfectly adequately and logically before.

I do have an iPad (iOS7.0.3 at present) and I never use the Reminders app precisely because it is counterintuitive not to have To Do items in my Calendar.

Every single Time Management course I have attended, read about or indeed lectured upon recommends as far as is practical keeping things "in one place", so why on earth have Apple split the perfectly useful To Do list off to a seperate app called Reminders?

You didn't (or don't) carry two paper based books - one a diary and one a to do list - so why introduce that into IT based systems?

Or am I just a grumpy old git who cannot stand the white-hot heat of technological change? 😕