Count 'em. 7 earth size planets circle Trappist 1

Still be an order of magnitude quicker and cheaper than sending actual probes just to do a fly by through an exo planetary system.

Maybe, maybe not.

You have to get the observatory craft out to the proper distance and have them slow down and hold station relative to the sun. This implies a pretty large spacecraft, with substantial engines...that have to be ignited decades or centuries after launch. No small challenge.

It's been awhile but I've seen mission plans that suggest with something like nuclear salt water engines the trip by could put a sophisticated probe in the proper area in about 100 years.

As I've said that is an order of magnitude faster and less complex than actually sending a flyby probe to an exoplanetary system.

There are plans afoot to send very, very small probes to nearby stars at very high speed already, so I expect you're wrong.

Breakthrough Starshot

The idea is you fling a small probe (or, more accurately, a lot of small probes) at high speed towards another star. Since they're small and lightweight, they're (relatively) easy to get up to interstellar speeds. They could reach Alpha Centauri in, perhaps, 20 years.

I don't know how they're going to get a strong enough signal back to Earth, but it's at least plausible they could reach another star system in a reasonable amount of time...