Rather than how much light, maybe it's more the coverage and how bright the coverage at a given place in the Kitchen (e.g., floor or counter) - the smaller the lights, the more you'll need for full coverage (& the more lights you need, the more electrical work, fixtures, & bulbs needed).

Regardless, I would not put in lights based on the current trend (or some nebulous future trend). In fact, some designers are moving away from recessed lights completely.

Unless you're selling in the next couple of years, I would go with what functions well for your needs, not how something looks or whether it's the latest "in thing".

2" might work fine for the Laundry Room, unless it's huge.

I have to disagree about coverage, we have 6" in our finished basement and 4" in the Kitchen and the basement lights definitely cover more area than the 4".