1- At the moment? Nobody. As for who rules life on earth, taken collectively the viruses make a pretty good argument... As for human technology, it has a few pretty impressive statistics, some less impressive, and thinking that multicellular=human...
2- Fair point, and it seems to be a vocal minority that wants to remain unicellular, a poll seems a good idea.
3b- Multicellular is a step towards the familiar, familiar scales, familiar vital processes, familiar mental processes, they are all likely to turn up in fairly short order. And there is incredible variety and potential in the unicellular world if you know how to look.
4- Yes, spikes are possible with multicellular organisms, but not the spikes we currently have, which would probably need to be thrown away...
5- It was matter many times our own volume and was remarked upon by the author. Also, it was taken intact...
6- because we will be too interested in the next big thing to worry about the next small thing...
1- If "ruling" mean "having the power to modify and destroy at will", then the answer is obviously the humans (although they use this power to fuck up the planet instead of making something constructive). Virus sure are numerous, but can they alterate the climate AT WILL? Can they modify entirely landscapes in a very short time? have they the power du WILLIGNLY WIPE OUT ENTIRE SPECIES, and create some
because they just want to? Humans can.
2- poll: multicell currently win by 10-2. vocal minority, uh?
3- familiar scales, yes, and yes, unicellulars sure have diversity. And potential. but potential need to be used. And evolution is like a tree (remember those evolutionnary trees). You can take an early turn, or a late turn. We just both want not to arrive somewhere we already explored.
Trust me, you can do something unfamiliar with something familiar. Civilizations games are sure funny with aliens, but they are also funny with humans, and even earthlings. Having humans at start dont mean you'll end with Earth's history.
4- throwing away our current spikes for better, bigger, more scale-adapted spikes dont seem to be a big problem for me. adaptation, evolution.
5- oh, yes, this. lucky dice throw? nice GM? The "taken intact" was for mitochondria. Because mitochondria needed to be absorbed. You didn't protest against this, did you? Had you said "symbiosis with mitochondria is too familiar. Let's stick without them"?
6- Then just be "the guy who take interest about small-scale changes" and do suggestion about cell-level ameliorations. You're likely to be supported.