Ronzo,
I suspect I'm one of those "newer divers" you refer to and I think this is a great discussion in the basic area.
As others have said, more eloquently than I probably can, freedom of choice is a concept I value highly. As I've said in several other posts throughout my few months reading SB, I am one of those people that carefully analyzes risk versus reward when making decisions like this.
I have made efforts both here and at my local shops to find buddies to dive with that haven't been very fruitful, so far, for whatever reason. Maybe I come across as a newbie "know it all"? I try to come across as s newbie eager to learn it all, but it's a fine line to walk.

In the end, I would prefer to always dive with someone else, but realistically I see that not being the case in the future. Schedules conflict, diving goals don't meet up, etc etc. If I find a mentor (or five) and/or some good diving buddies I won't be diving solo any time soon, but for now I haven't found that elusive creature.
When I consider the idea of solo diving, in a pool or otherwise, I take a lot of factors into consideration. Am I truly solo, or is there someone that is "responsible" to watch out for me, or whom I know
will watch out for me even if it isn't their responsibility? Am I planning anything that is at the edge of my skill or competence? Am I using new gear or "tried and true" equipment? Am I doing anything deep? (This is arguably an invalid concern because you can die in a couple feet of water just as easily as you can die in 100 feet of water.) When was my last dive (I'm still new so all my dives are within the last 6 months) and was I comfortable with everything then? Do I feel well. Do I have time to postpone this dive until I can find a partner? The list goes on and on.
I have been a member of a Search and Rescue team for 11 years and was military before that. I'm well versed in my own "panic response" and how to deal with any emergency. I'm trained in first aid (arguably no help for myself underwater but it helps with the "panic response") and I know my limits very well and keep well away from them when not in "ideal" situations. Ideal here being partnered rather than solo. All these things I consider any time and every time I'm thinking about any kind of solo diving.
So far I have done exactly one "solo" in a pool with a lifeguard present and my wife and daughter "snorkeling" directly above me. I advocate learning your gear and your sport. I advocate practicing skills as often as you can, when it's reasonably safe to do so. Sometimes that means doing things in a pool alone, even if it's not the ideal. I am a person that gets immersed into whatever hobby I am interested in, and as such I dedicate a lot of "mental" time to it. I often can't dedicate as much physical time to an activity. As such, the times I can commit to active, physical, participation I consider very valuable and I'm willing to choose solo over "no go" for some of those times.
I chose not to do a "real" solo dive on my vacation to Hawaii because I decided I am simply too inexperienced and didn't have what I consider to be the minimum requirements for soloing (redundant air etc) and it's really not that important for me to dive at every possible opportunity at this stage in my diving career. Reasonable or not, I don't consider "solo" in a pool the same level of concern. It's my confidence in myself (perhaps it's misguided confidence) based on other activities completely unrelated to SCUBA. Perhaps it's just my eagerness and lack of experience at "all the possibilities" that makes me more willing to "overlook" them in a pool? I tend to doubt that, though, as I am very cautious about the choices I make and will always "thumb" a bad situation even if it's just a "gut feeling" that something is amiss with no verifiable evidence of it.
I can see myself doing the occasional solo in the future, simply because I'm comfortable with my own skill and doing things on my own. I've solo hiked and camped. I solo climb, on occasion, well under my limits and at low heights, and I solo kayak, bike etc etc. I don't expect diving to be much different. I'm realistic in the requirements of doing things solo and the ramifications should problems arise. As such, I believe solo is a valid choice for many people, me included.
I don't believe it's the right choice for all occasions or all people, which is why I tend to give myself and others the advice that they wait to solo. I will always tell people it's their choice, though, and try to list all the possibilities I can come up with that they (and I) should consider as potential issues before making the choice to solo.
I really appreciate these threads as it often gives people a lot of insight (if they're willing to look for it) that they may or may not have had. It also gives very personal accounts, yours included, of the finality the "issues" can take even for experienced divers. Reality checks are very important.
Thanks for the discussion.