Do you think going from optical to totally lossless audion is necessary for most people?
This is a loaded question. Again it all depends on your setup.
For the average person, right now, I would say no. Optical sound works fine for the average person.
First let me re-phrase what I was saying before. The investment of going from built-in tv speakers to a simple optical 5.1 system is huge. IMHO it should be a priority before going from 720 to 1080p.
To answer your question more in depth, optical vs lossless has several variables.
1) Your receiver is obviously important. If it's an old school 2.0 setup then stick with optical. I am assuming by your question, you already know this and have a Dolby True HD or equivalent compatibility.
2) Speakers - it takes a very high quality speaker to actually get the most out of lossless sound. (also, if you live in an apartment or condo, you may not be able to really crank your subwoofer - something to consider)
3) The types of films you watch. If you are into 'talking heads' movies, then you are only really using your center channel anyway. Doesn't make a whole lot of sense to dump money into a lossless system. Take that money and buy a top-of-the-line center channel speaker. Older movies also don't really take advantage of 5.1. Even movies from the 80's only used Dolby SR for their original mix. Even if they are remastered, they weren't 'designed' like movies sound today.
The leads into my next point
4)On the other hand, some movies are made for sound. Star Trek, Transformers, District 9 (one of my personal favorite sounding movies), those films invest a tonne to get incredible sound. They have teams of sound designers that work with the mixers to really take things to the next level. You won't be able to get everything out of your speakers unless you build a theatrical screening room.
Personally, I have a lossless system and love it, but I am also in the industry, so it's a priority for me. I have been in the mixing room for several films and a lot of them are set up relatively similar to home systems so you can put a system together for 4 or 5 grand that sounds the same as the smaller studio films mixing facility!
If I am excited about a tent-pole movie, I always watch it in theaters, you just can't beat the sound in a theater setting. To me, the sound is the main reason to go to a theater (that and the film print intangible that is slowly disappearing.)
I hope I answered your question. I tried to keep it simple without getting to heavy into bitrate, sample rate, bit depth etc,