I don't see many of those as being credible reasons not to pursue it:

i) recovery of wings/engines - the US military would have had you believe 10 years ago that they could send a 2 tonne bomb down a chimney from great altitude, so this shouldn't pose a significant problem for the engines. A bit of ingenuity about the wings (making them swing wing and folding into the body?) would solve the wing issue.

ii) using smaller rockets/slower speeds (but still increased over current speeds) for shorter flights would still bring a benefit.

iii) there wouldn't be an issue with flight corridors: the rocket hybrids would fly at around twice the height of a conventional jet airliner.

iv) heat sensitivity could be worked around by combining technologies, i.e. why not ceramic coat the composites around heat sensitive areas?

v) emissions, I don't really have an understanding of how rocket engines compare to jet engines on emissions, but I don't see any reason why we couldn't see the improvements in rocket engine efficiency that we've seen in other forms of engine efficiency once the green focus has been turned on them.

You can't avoid the basic scientific fact that rockets gobble through their entire fuel load in seconds/minutes. That, and the fact that they are so inherently dangerous, will always mean that they are unsuitable for civil transport.

There are limits to what can be done regarding reliability. A rocket, by its very nature, packs a huge amount of explosive power into as small a space as possible. Their very modus operandi is the release of that explosive power in a s controlled a manner as possible. That is a very, very difficult thing to do.
Even after almost 100 years of building sophisticated and advanced liquid fueled rockets we still have major problems with the things. No matter how well engineered they are, they have to contain massive amounts of energy and store corrosive and sensitive fuels at often extremely low temperatures and high pressures. Trying to make metals, plastics, rubbers, sealants, valves, pumps, plumbing etc that can withstand all of these factors is very hard.

And after the posts of those of us who know a bit about these things, you should be able to ascertain by now that, from a fuel consumption point of view, a rocket is nowhere near as efficient as other types of reaction engines.

Take the time to watch a live rocket launch and you will see how sensitive they are and how cautious you have to be when handling all that power.

(i) if you go for the recovery option, simply the logistics alone would be prohibitively expensive. Can you imagine recovering, inspecting, and refitting those wings 4 or 5 times a day per aircraft? Swing wing is a way forward, but you then get into weight / cost / complexity issues.

(ii) yep, but the reduced benefits bring reduced income, so the business case looks less attractive

(iii) you still need to take off and land

(iv) what happens when you get a bird strike which damages the ceramic? Would you be happy to fly at 2,000mph on an aircraft where the thermal barrier was damaged?

(v) you could see improvements, but even with significant development you're still going to have more emissions in aboslute terms

For how long can a hybrid rocket produce meaningful thrust?

Perhaps we need to research transporters, a la Star Trek.

And that is the crux of the problem with any rocket, liquid fueled, solid fueled or hybrid - they just use their fuel too rapidly for any practical commercial application.

Remind me why a rocket was proposed - apparently for atmospheric flight (at 30,000ft)?

Why would you even consider a rocket at that altitude?

quite

rocket advantages: extreme acceleration and can be used outside the oxygen-bearing atmosphere

neither of those are advantages for passenger flights

And they are ditched after every race. Commercial airlines wouldn't be mad keen to throw away a substantial part of the aircraft after each flight.