"Do you think those changes makes arcanists, bards, rogues and rangers too strong?"
No, I just feel their strength lies in other areas. Magic Users, in AD&D were focused entirely on their magic spells, giving everything in life, including physical agility for the power that one day (at 11th level and above, say, would make them the strongest members of the group. Who could argue the 18th level arch-mage could take any other class, if he could set the environment to his liking? Being weak at 1st level, made his spells most useful, when called upon while regulating him to stand behind the tanks in fights. (Pretty realistic, I think). And a good GM should write the story so every character has a moment to shine no matter what his/her talents/powers are.
I do understand the need for balance, especially at high levels, when all should be strong, but the party compliments each other. The spells of the mage and cleric augment the others when the need exists, the way the rogues trap-defeating abilities circumvent possible deaths for the rest of the party. A balanced party with each member excelling in his/her chosen area (and surely spending years focusing on just those items) beats out a party of balanced individuals, anyday.
Which is exactly what happened in 4th edition. Not only is it an unrealistic "video game" on table-top format, but all the characters are the same. It is metagamed, so even if powers are called different things, they are the same. A first level wizard can stand nearly toe-to-toe with a first level fighter, with ease.
Plus, 4th edition gives an unreal amount of hit points to characters and monsters at first level. Some feel this adds survivability to characters, but since the monsters get the same, it just makes 1st level battles take the same time high level battles take in 3.5 or any other edition and makes the whole concept unweildy and video-game like.
I do agree with max hit points at 1st level, and tend to use an average at every other level, as well as a liberal point buy system for abilities, etc. Dice rolling should be for encounters, all characters should have an even chance at the start of the game, in their chosen vocations, and it should all take a back-seat to role-playing. With good role-players, it is possible to role-play nearly any encounter with characters of any power, and never worry about game mechanics or lining up feats to have the toughest character or whatever. All that numbers stuff can really take from the game, if you let it.
"I never got the rogue HP, compared to clerics. They are more physically fit, they focus completely on physical abilities, while clerics kneel around begging for divine magic."
Not so, Kaeyoss. The clerics of D&D are not the weak temple priests, but more knights of their own accord, trained in battle. These battle clerics train in the wear of armor and use of weapons, perhaps giving up divine power (who knows?) for survivability in places their temple brethren dare never tread. While not as proficient as fighter-types or the knights they rode with, they surely had more hit points than skill-based characters (practicing picking locks and pockets in secret lairs) or arcanists (who spend countless years in dark towers studying musty tomes.
My games do tend to rely more on realism than perhaps the games of others. So perhaps my view is skewed. My world tends to be low in quanity of magic while high in value and magic is a strong ally for those few who possess it and must sacrifice much to have it.