This is something I've begun to realize: You consider card drawing to be a valueless spell effect. The +1/+1 should still cost a mana, but the card drawing needs to reflect a cost as well. I get that you are restricting it to artifact creatures only, but you still can't have free +1/+1 boosts, and free card drawing is worse.
Although it is true that one of the cycles I've featured and one card of the day have "Draw a card" as an effect, I realize the value of drawing a card. Compare this to Mishra's Bauble and Urza's Bauble. The only difference on those is that the card draw is at the beginning of the next turn's upkeep, and that they can be used at any time. The drawback on this is that you can't cast it unless there is an Artifact Creature on the table.
Let's do a thought experiment, though. Imagine I play a colorless land on turn one, then the Machina Serpent. It is a 1/1 with haste. Then, I play this card on it. It is a 2/2 with haste, I've drawn a card, and my opponent will probably take two damage on the first turn with no real cost to me.