SMD electronics parts over Through Hole

Aside from its size, what else are the advantage of SMD components over through hole components? Why should I consider in choosing between using a SMD or Through Hole components as my electronic components?

Availability, for one.
Component manufacturers are now only introducing newer products in SMT format. Older legacy components in thru hole packages, are being discontinued all the time

Second, they have much better thermal characteristics, which is important for dense power supplies.

Also in high frequency circuits, the passive components usually have lower parasitics.

Lastly, the ability to populate both sides of the board is a big plus in compact projects.

You can put two components in the "same" space; one on top and one on the bottom.

What are you designing, this will also have an influence on component choice....
Other than that I have been doing SMD design since the late 1980s, initially mixed (PTH/SMD) with quite a few IC's in PTH packages, this soon tapered off with the appearance of SOIC devise... Now apart from power components and connectors every design is almost exclusively SMD. Fir digital you need it to reduce size, signal loop areas and transmission line length to cater for the high speed interfaces... Analogue it reduces loop areas as well as other advantages.... For both ease of assembly, control of thermal aspects of the design, increased functionality...
Its a bit of a strange question for the 21st Century... Look at ALL the electronics round you the majority are SMD based, the functionality you achieve for a given size etc.

In addition to all above mentioned, SMD components allow PCA assembling by automated process, with pick-and-place machines, reducing significantly overall cost of product, aswell elliminating human error on the production process, improving reliability.

I second what all of these guys said. Take a board with 100 components, pretty simple. Loading it up on a pick-and-place machine with all SMD parts takes an hour or two. Having the machine place 100 parts is going to take about 10 minutes (and that's a really slow machine, placing only 10 parts per minute). Reflow, and boards are done in a total of a couple of hours.

Now take a through-hole board. Not only does each part have to be manually soldered (or manually tacked then wave/selective soldered), but prior to insertion, each lead needs to be bent at a 90° angle. After installation, each lead needs to be clipped to flush (or almost flush) with the board. It's really time consuming, and you will pay for it in assembly charges.

The only justification I would have for designing a through-hole board is if I only planned on building one and had no future use for it. Other than that, SMD is the only way to go!