Some differences from my perspective:

- SOA/ESB in the 2000s was driven more by business, less by available tech. As an example of what I mean here, SOA folks would usually talk about decomposing business process. E.g. Amazon sells something, there's a "shopping cart" service, a "payment" service, and a "delivery" service. (I'm simplifying, but you get the point) Modern microservies are way more granular than that, and it could be that you have 5 tech-oriented services that compose to a single sub-step of a business process. The original SOA idea had the concept right, but was (IMHO) still too coarse to make the idea work.

- Several enabling techs that came since then (containerization being an example key one) didn't exist then, which made doing the same thing 5x more painful. So the tech just grew up.

- On the data side, SOA/ESB was driven by XML and XML Schema. As someone who practiced a lot of that, it was really painful to use a document markup language to do structured data exchange. XML was popular because in the age of proprietary formats it was the first open, text-based, non-license encumbered format. So don't get me wrong, there wasn't anything better at the time, but that didn't make XML actually good for the job. Note this is not a comment that JSON is better. In 2018 we're in a world where open data standards are the default. So it's not XML vs. JSON. It's XML vs. the entire rest of the world you have so many options.

- Performance improved, how many years of Moore's law, storage & memory in between? This may not seem like a big deal, but it is. Since 2000 we gained so much in computing power, that we can afford to slather on another 10 layers of abstraction to make microservices easier on ourselves.

- Software support improved. Go back to 2001 and scaffold a java app that worked with WSDL and SOAP. Then go check out 2018's serverless framework and scaffold a node.js serverless function. Back in 2001 you may have been manually downloading JARs and putting them in a lib folder, then checking that into cvs. In 2018 it's yarn install whatever, saving dependency structure (but not binaries) in git. This amounts to hours of extra work the developer is no longer doing. Greg Lemond, the famous cyclist, was inadvertently talking about software when he said: "It never gets easier, you just go faster".

- Infrastructure improved. As with the previous point, there are hours of work you're not doing, that lets you focus on your microservice. For example, almost no one who writes a microservice admins the server it runs on. Why would you take such care to admin a single box? Just execute it and spin up another. The average developers of 2001 would be mind-blown.

...But some things stay the same....namely there's nothing free in this world, and everything's a tradeoff.

- Service decomposition to the right level is still really tricky and people regularly screw it up.

- Being able to write your system in 10 different languages is nice for flexibility of hiring, speed, and team independence. But then of course you have to maintain 10 different languages worth of software.

- We've traded debugging of simple stack traces in monoliths for ultra-complex network inspection setups where we debug the failure to pass a parameter to a remote function through a nightmare of complexity -- through the tech stacks of both services, through the networking layer, through the containerization layer, through the orchestration layer, etc. etc. Monoliths were not without their charms.