@dor: LED's alone are pointy light sources, their intensity is comparable to incandescent filaments, but single lED is of too low output (the 1W is just on the border for reliable assembly, so about 80..90lm in 5500K CRI70), so you have to use many of them for the complete task.
And then it is the way, how the LED's are assembled together, what make them diffused light source. But that is not problem of the LED's, but of the way, how they are assembled into larger module.
LED's are different light source with different characteristics, so you have to use different approach when using them for given tasks. So for streetlights, an approach used for HID (use high output source cram,med onto small space and then make a beam pattern of it via common otics) simply won't work with LED's...
Each chip should have it's own optics, so it can not be the one common lens for the complete lantern, that does not work.
But as they are small, mold the optic assembly for e.g.
28LED chip module with each LED chip having it's own lens into
one piece of plastic and so get a module sufficient for 3..4m high streetlights, spaced 9..15m for small roads (with about 25W input including ballast losses and ~1800lm output of really uniform illumination - I assume you driuve the 28 "1W" leds at only 20W in total, so they won't degrade as fast).
But of course all have to be manufactured with good quality control, so the shop in the examples does not give me enough trust for reliable product (mainly the long term stability of the used materials - shape and mainly the transparency), but I want to use it as an example, how to really use the LED's.
@DetroitTwoStroke:
The induction lifetime may be rated at 50..100khours, but I'm a bit skeptical about the electronic actually making it in the real life. And even when the electronic could be made to reach that life, there is no reason, why the LED's could not - as their degradation mechanisms are exactly the same as for any semiconductor device, so the life is only a matter of design, manufacturing quality and operating conditions.
Moreover there is no means to really prove such claim with valid test - it would simply take too long and it popped out, then no manufacturer actually had any valid reliability test data for that. And this was the base, why life expectancy claims above 25khours were in fact banned in the US - as up to now all of them were proved to be false (= there was no proof of their validity).
For streetlights you have to achieve even illumination level, so equal just below the fixture, as between the poles. And that mean, then the fixture have to throw more than 10x the intensity in the 60degree angle (from vertical) than straight down. Such pattern is impossible to make without the light source being small and high intensity or with huge optics.
The best from the "vacuum technology" in this aspect are the MH's, as e.g. 6000lm unit have all light source in ~1cm ball, so to get reasonable pattern, you need ~25cm lens/reflector assembly. The second best are the HPS, which are quite long, narrow diameter. But in order to make a 5m wide strip, they still suffice with rather reasonable optics size.
LPS do not allow any reasonable optical; control due to their size, so a LPS fixture have to have ~2..3x the lumen output than HPS for the same minimum illumination level, so their application become restricted to places, where their monochromatic light is of added value (so places with frequent and dense fog,...)
Other complication with all of these is their omnidirectional character. To half of the light have to be "bended" and half returned to the opposite side. That is problem, because for the first half you would need a refractor, while for the second the reflector optic. But you can not have both without one interfering with the other one. So therefore most designs use reflectors to create the far reaching wings and fill the rest with rather direct light form the lamp. But that create ~3..4x overillumination just below (or nearby) the pole, so you end up with the need of about 2x higher raw lamp lumen output compare to the total lumens, when all the area would be lit evenly just on the specified minimum level.
The trick with LED's is, the 1x1mm size of the 1W chip make one inch lens (what is the spacing of the 1W chips) already 25x larger than the light source, to get an equivalent with 20cm induction would need a lantern about 5m in diameter...
And the LED's have yet another advantage: They emit all their light only into one half-space, so with only refractor (=lens) optics you are able to shape the beam so, it make the even stripe of light, so you really utilize nearly all of the light output, so you suffice with ~50..60% of the raw lumen output compare to the best HID's. And the even illumination would even give you better visibility.